Light/Dark theming

README.md

@@ -1,4 +1,4 @@
-# RpgRoller
+# RpgRoller
 
 RpgRoller is an ASP.NET Core and Blazor Server app for lightweight tabletop campaign play, character sheets, and dice workflows.
 
@@ -54,7 +54,8 @@ Frontend:
 - `RpgRoller/Components/RpgRollerApiClient.cs`: browser API client for write actions
 - `RpgRoller/Components/WorkspaceQueryService.cs`: browser-facing read client for workspace data
 - `RpgRoller/wwwroot/js/rpgroller-api.js`: browser interop for auth forms, session storage, SSE wiring, and DOM helpers
-- `RpgRoller/wwwroot/styles.css`: app styling and responsive layout
+- `RpgRoller/wwwroot/styles.css`: app styling, light and dark theme variables, and responsive layout
+- `RpgRoller/wwwroot/images/light.png` and `RpgRoller/wwwroot/images/dark.png`: themed workspace background art
 
 Current repo note:
 
@@ -75,6 +76,7 @@ Current repo note:
 - Supported campaign rulesets: D6 System, D&D 5e, and Rolemaster
 - Account registration, login, session-based auth, and role-aware authorization
 - Admin tools for user listing, role updates, account deletion, and direct SQLite database download
+- Per-user light and dark theme preference with OS-based initial selection
 - Campaign creation, roster reads, participant-scoped visibility, and owner and admin deletion
 - Character creation, activation, owner transfer, campaign reassignment or unlinking, and owner and admin deletion
 - Skill groups with reusable defaults plus skill and skill-group create, edit, reassign, and delete flows

RpgRoller.Tests/Api/AuthApiTests.cs

@@ -1,4 +1,4 @@
-namespace RpgRoller.Tests;
+namespace RpgRoller.Tests;
 
 public sealed class AuthApiTests(WebApplicationFactory<Program> factory) : ApiTestBase(factory)
 {
@@ -12,8 +12,7 @@ public sealed class AuthApiTests(WebApplicationFactory<Program> factory) : ApiTe
         Assert.Equal("alice", registerResult.Username);
         Assert.Contains(registerResult.Roles, role => string.Equals(role, "admin", StringComparison.OrdinalIgnoreCase));
 
-        var duplicate = await client.PostAsJsonAsync("/api/auth/register",
+        var duplicate = await client.PostAsJsonAsync("/api/auth/register", new RegisterRequest("alice", "Password123", "Alice 2"));
-            new RegisterRequest("alice", "Password123", "Alice 2"));
         Assert.Equal(HttpStatusCode.BadRequest, duplicate.StatusCode);
 
         var loginResult = await client.PostAsJsonAsync("/api/auth/login", new LoginRequest("alice", "Password123"));
@@ -21,13 +20,39 @@ public sealed class AuthApiTests(WebApplicationFactory<Program> factory) : ApiTe
 
         var me = await GetAsync<MeResponse>(client, "/api/me");
         Assert.Equal(registerResult.Id, me.User.Id);
+        Assert.Null(me.User.ThemePreference);
         Assert.Null(me.ActiveCharacterId);
         Assert.Null(me.CurrentCampaignId);
 
+        var themeUser = await PutAsync<UpdateThemePreferenceRequest, UserSummary>(client, "/api/me/theme", new("dark"));
+        Assert.Equal("dark", themeUser.ThemePreference);
+
+        var themedMe = await GetAsync<MeResponse>(client, "/api/me");
+        Assert.Equal("dark", themedMe.User.ThemePreference);
+
         var invalidLogin = await client.PostAsJsonAsync("/api/auth/login", new LoginRequest("alice", "wrong-password"));
         Assert.Equal(HttpStatusCode.BadRequest, invalidLogin.StatusCode);
     }
 
+    [Fact]
+    public async Task ThemePreferenceEndpoint_RequiresAuthAndValidTheme()
+    {
+        using var factory = CreateFactory();
+        using var client = factory.CreateClient(new() { AllowAutoRedirect = false });
+
+        var unauthorized = await client.PutAsJsonAsync("/api/me/theme", new UpdateThemePreferenceRequest("dark"));
+        Assert.Equal(HttpStatusCode.Unauthorized, unauthorized.StatusCode);
+
+        var unauthorizedInvalid = await client.PutAsJsonAsync("/api/me/theme", new UpdateThemePreferenceRequest("sepia"));
+        Assert.Equal(HttpStatusCode.Unauthorized, unauthorizedInvalid.StatusCode);
+
+        await RegisterAsync(client, "theme-api", "Password123", "Theme Api");
+        await LoginAsync(client, "theme-api", "Password123");
+
+        var invalid = await client.PutAsJsonAsync("/api/me/theme", new UpdateThemePreferenceRequest("sepia"));
+        Assert.Equal(HttpStatusCode.BadRequest, invalid.StatusCode);
+    }
+
     [Fact]
     public async Task UsernamesEndpoint_RequiresAuthAndReturnsAlphabeticalList()
     {
@@ -54,10 +79,7 @@ public sealed class AuthApiTests(WebApplicationFactory<Program> factory) : ApiTe
 
         await RegisterAsync(client, "proxy-user", "Password123", "Proxy User");
 
-        using var request = new HttpRequestMessage(HttpMethod.Post, "/api/auth/login")
+        using var request = new HttpRequestMessage(HttpMethod.Post, "/api/auth/login") { Content = JsonContent.Create(new LoginRequest("proxy-user", "Password123")) };
-        {
-            Content = JsonContent.Create(new LoginRequest("proxy-user", "Password123"))
-        };
         request.Headers.TryAddWithoutValidation("X-Forwarded-Proto", "https");
 
         using var response = await client.SendAsync(request);

RpgRoller.Tests/HostingCoverageTests.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Infrastructure;
@@ -159,6 +159,7 @@ public sealed class HostingCoverageTests
             usersColumns.Add(usersTableInfoReader.GetString(1));
 
         Assert.Contains("Roles", usersColumns);
+        Assert.Contains("ThemePreference", usersColumns);
 
         using var usersRoleCommand = verifyConnection.CreateCommand();
         usersRoleCommand.CommandText = "SELECT Roles FROM Users WHERE UsernameNormalized = 'LEGACY-ADMIN';";
@@ -214,6 +215,11 @@ public sealed class HostingCoverageTests
         retryHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260414204309_AddRolemasterAutoRetry';";
         var retryHistoryCount = Convert.ToInt32(retryHistoryCommand.ExecuteScalar());
         Assert.Equal(1, retryHistoryCount);
+
+        using var themeHistoryCommand = verifyConnection.CreateCommand();
+        themeHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260518183838_AddUserThemePreference';";
+        var themeHistoryCount = Convert.ToInt32(themeHistoryCommand.ExecuteScalar());
+        Assert.Equal(1, themeHistoryCount);
     }
 
     [Fact]
@@ -359,6 +365,11 @@ public sealed class HostingCoverageTests
         retryHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260414204309_AddRolemasterAutoRetry';";
         var retryHistoryCount = Convert.ToInt32(retryHistoryCommand.ExecuteScalar());
         Assert.Equal(1, retryHistoryCount);
+
+        using var themeHistoryCommand = verifyConnection.CreateCommand();
+        themeHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260518183838_AddUserThemePreference';";
+        var themeHistoryCount = Convert.ToInt32(themeHistoryCommand.ExecuteScalar());
+        Assert.Equal(1, themeHistoryCount);
     }
 
     [Fact]
@@ -481,6 +492,15 @@ public sealed class HostingCoverageTests
 
         Assert.Contains("FumbleRange", skillGroupColumns);
 
+        using var usersTableInfoCommand = verifyConnection.CreateCommand();
+        usersTableInfoCommand.CommandText = "PRAGMA table_info('Users');";
+        using var usersTableInfoReader = usersTableInfoCommand.ExecuteReader();
+        var usersColumns = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+        while (usersTableInfoReader.Read())
+            usersColumns.Add(usersTableInfoReader.GetString(1));
+
+        Assert.Contains("ThemePreference", usersColumns);
+
         using var authorizationRolesHistoryCommand = verifyConnection.CreateCommand();
         authorizationRolesHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260226170000_AddAuthorizationRoles';";
         var authorizationRolesHistoryCount = Convert.ToInt32(authorizationRolesHistoryCommand.ExecuteScalar());
@@ -490,5 +510,10 @@ public sealed class HostingCoverageTests
         retryHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260414204309_AddRolemasterAutoRetry';";
         var retryHistoryCount = Convert.ToInt32(retryHistoryCommand.ExecuteScalar());
         Assert.Equal(1, retryHistoryCount);
+
+        using var themeHistoryCommand = verifyConnection.CreateCommand();
+        themeHistoryCommand.CommandText = "SELECT COUNT(*) FROM \"__EFMigrationsHistory\" WHERE \"MigrationId\" = '20260518183838_AddUserThemePreference';";
+        var themeHistoryCount = Convert.ToInt32(themeHistoryCommand.ExecuteScalar());
+        Assert.Equal(1, themeHistoryCount);
     }
 }

RpgRoller.Tests/Services/ServiceAuthTests.cs

@@ -1,4 +1,4 @@
-namespace RpgRoller.Tests;
+namespace RpgRoller.Tests;
 
 public sealed class ServiceAuthTests
 {
@@ -74,4 +74,26 @@ public sealed class ServiceAuthTests
         var usernames = ServiceTestSupport.GetValue(service.GetUsernames(session));
         Assert.Equal(["amy", "bob", "zoe"], usernames);
     }
+
+    [Fact]
+    public void UpdateThemePreference_RequiresAuthAndPersistsSupportedTheme()
+    {
+        using var harness = ServiceTestSupport.CreateHarness();
+        var service = harness.Service;
+
+        service.Register("theme-user", "Password123", "Theme User");
+        var session = ServiceTestSupport.GetValue(service.Login("theme-user", "Password123")).SessionToken;
+
+        var unauthorized = service.UpdateThemePreference(string.Empty, "dark");
+        var invalid = service.UpdateThemePreference(session, "sepia");
+        var updated = service.UpdateThemePreference(session, "DARK");
+
+        Assert.False(unauthorized.Succeeded);
+        Assert.False(invalid.Succeeded);
+        Assert.True(updated.Succeeded);
+        Assert.Equal("dark", ServiceTestSupport.GetValue(updated).ThemePreference);
+
+        var me = ServiceTestSupport.GetValue(service.GetMe(session));
+        Assert.Equal("dark", me.User.ThemePreference);
+    }
 }

RpgRoller.Tests/Services/ServicePersistenceTests.cs

@@ -1,4 +1,4 @@
-namespace RpgRoller.Tests;
+namespace RpgRoller.Tests;
 
 public sealed class ServicePersistenceTests
 {
@@ -22,8 +22,7 @@ public sealed class ServicePersistenceTests
         var otherSession = ServiceTestSupport.GetValue(service.Login("other", "Password123")).SessionToken;
 
         var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(gmSession, "Main", "d6"));
-        var ownerCharacter =
+        var ownerCharacter = ServiceTestSupport.GetValue(service.CreateCharacter(ownerSession, "Owner Character", campaign.Id));
-            ServiceTestSupport.GetValue(service.CreateCharacter(ownerSession, "Owner Character", campaign.Id));
 
         Assert.False(service.GetMe(string.Empty).Succeeded);
         Assert.False(service.CreateCampaign(gmSession, "", "d6").Succeeded);
@@ -80,8 +79,7 @@ public sealed class ServicePersistenceTests
             Assert.NotNull(db.Users.Single(u => u.UsernameNormalized == "OWNER").ActiveCharacterId);
         }
 
-        var skill = ServiceTestSupport.GetValue(service.CreateSkill(ownerSession, ownerCharacter.Id, "Stealth", "2D+1",
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(ownerSession, ownerCharacter.Id, "Stealth", "2D+1", 1, true));
-            1, true));
         Assert.False(service.UpdateSkill(ownerSession, skill.Id, "", "2D+1", 1, true).Succeeded);
         Assert.False(service.UpdateSkill(string.Empty, skill.Id, "Stealth", "2D+1", 1, true).Succeeded);
         Assert.False(service.UpdateSkill(ownerSession, skill.Id, "Stealth", "bad", 1, true).Succeeded);
@@ -111,17 +109,13 @@ public sealed class ServicePersistenceTests
         var gmSession = ServiceTestSupport.GetValue(service.Login("gm-rm-persist", "Password123")).SessionToken;
         var ownerSession = ServiceTestSupport.GetValue(service.Login("owner-rm-persist", "Password123")).SessionToken;
 
-        var campaign =
+        var campaign = ServiceTestSupport.GetValue(service.CreateCampaign(gmSession, "Rolemaster Persistence", "rolemaster"));
-            ServiceTestSupport.GetValue(service.CreateCampaign(gmSession, "Rolemaster Persistence", "rolemaster"));
         var character = ServiceTestSupport.GetValue(service.CreateCharacter(ownerSession, "Loremaster", campaign.Id));
-        var group = ServiceTestSupport.GetValue(service.CreateSkillGroup(ownerSession, character.Id, "Perception",
+        var group = ServiceTestSupport.GetValue(service.CreateSkillGroup(ownerSession, character.Id, "Perception", "d100!+25", 0, false, 5));
-            "d100!+25", 0, false, 5));
+        var skill = ServiceTestSupport.GetValue(service.CreateSkill(ownerSession, character.Id, "Read Runes", "d100!+35", 0, false, group.Id, 3, true));
-        var skill = ServiceTestSupport.GetValue(service.CreateSkill(ownerSession, character.Id, "Read Runes",
-            "d100!+35", 0, false, group.Id, 3, true));
 
         using var reloadedHarness = ServiceTestSupport.CreateHarnessFromPath(harness.DbPath);
-        var reloadedSheet =
+        var reloadedSheet = ServiceTestSupport.GetValue(reloadedHarness.Service.GetCharacterSheet(ownerSession, character.Id));
-            ServiceTestSupport.GetValue(reloadedHarness.Service.GetCharacterSheet(ownerSession, character.Id));
 
         var reloadedGroup = Assert.Single(reloadedSheet.SkillGroups, current => current.Id == group.Id);
         Assert.Equal(5, reloadedGroup.FumbleRange);
@@ -130,4 +124,22 @@ public sealed class ServicePersistenceTests
         Assert.Equal(3, reloadedSkill.FumbleRange);
         Assert.True(reloadedSkill.RolemasterAutoRetry);
     }
+
+    [Fact]
+    public void UserThemePreference_PersistsAcrossDatabaseReload()
+    {
+        using var harness = ServiceTestSupport.CreateHarness();
+        var service = harness.Service;
+
+        service.Register("theme-persist", "Password123", "Theme Persist");
+        var session = ServiceTestSupport.GetValue(service.Login("theme-persist", "Password123")).SessionToken;
+
+        var updated = ServiceTestSupport.GetValue(service.UpdateThemePreference(session, "dark"));
+        Assert.Equal("dark", updated.ThemePreference);
+
+        using var reloadedHarness = ServiceTestSupport.CreateHarnessFromPath(harness.DbPath);
+        var me = ServiceTestSupport.GetValue(reloadedHarness.Service.GetMe(session));
+
+        Assert.Equal("dark", me.User.ThemePreference);
+    }
 }

RpgRoller/Api/MeEndpoints.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Http.HttpResults;
 using RpgRoller.Contracts;
 using RpgRoller.Services;
 
@@ -14,6 +14,12 @@ internal static class MeEndpoints
             return ApiResultMapper.ToApiResult(result);
         });
 
+        group.MapPut("/me/theme", Results<Ok<UserSummary>, BadRequest<ApiError>, UnauthorizedHttpResult> (UpdateThemePreferenceRequest request, HttpContext context, IGameService game) =>
+        {
+            var result = game.UpdateThemePreference(context.GetRequiredSessionToken(), request.ThemePreference);
+            return ApiResultMapper.ToApiResult(result);
+        });
+
         return group;
     }
 }

RpgRoller/Components/App.razor

@@ -1,4 +1,4 @@
-@using RpgRoller.Components.Pages.HomeControls
+@using RpgRoller.Components.Pages.HomeControls
 @attribute [ExcludeFromCodeCoverage]
 
 <!DOCTYPE html>
@@ -8,6 +8,12 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
     <base href="@BaseHref"/>
     <title>RpgRoller</title>
+    <script>
+        document.documentElement.dataset.theme = window.matchMedia &&
+            window.matchMedia("(prefers-color-scheme: dark)").matches
+            ? "dark"
+            : "light";
+    </script>
     <link rel="stylesheet" href="@Assets["styles.css"]"/>
     <link rel="preconnect" href="https://fonts.googleapis.com">
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>

RpgRoller/Components/Pages/HomeControls/AppHeader.razor

@@ -40,6 +40,13 @@
             }
         </div>
         <a href="" class="logout-link" @onclick:preventDefault="true" @onclick="LogoutRequested">Logout</a>
+        <button type="button"
+                class="theme-toggle"
+                aria-label="@ThemeToggleAriaLabel"
+                title="@ThemeToggleAriaLabel"
+                @onclick="ThemeToggleRequested">
+            <span aria-hidden="true">@ThemeToggleLabel</span>
+        </button>
         @if (MenuItems.Count > 0)
         {
             <div class="header-menu-wrap">

RpgRoller/Components/Pages/HomeControls/AppHeader.razor.cs

@@ -12,37 +12,64 @@ public partial class AppHeader
         return item.OnSelected?.Invoke() ?? Task.CompletedTask;
     }
 
-    [Parameter] public string Title { get; set; } = "RpgRoller";
+    private string ThemeToggleAriaLabel => string.Equals(Theme, "dark", StringComparison.OrdinalIgnoreCase) ? "Switch to light theme" : "Switch to dark theme";
 
-    [Parameter] public UserSummary? User { get; set; }
+    [Parameter]
+    public string Title { get; set; } = "RpgRoller";
 
-    [Parameter] public bool ShowCampaign { get; set; }
+    [Parameter]
+    public UserSummary? User { get; set; }
 
-    [Parameter] public IReadOnlyList<CampaignSummary> Campaigns { get; set; } = [];
+    [Parameter]
+    public bool ShowCampaign { get; set; }
 
-    [Parameter] public Guid? SelectedCampaignId { get; set; }
+    [Parameter]
+    public IReadOnlyList<CampaignSummary> Campaigns { get; set; } = [];
 
-    [Parameter] public string CampaignSelectId { get; set; } = "header-campaign-select";
+    [Parameter]
+    public Guid? SelectedCampaignId { get; set; }
 
-    [Parameter] public EventCallback<ChangeEventArgs> CampaignSelectionChanged { get; set; }
+    [Parameter]
+    public string CampaignSelectId { get; set; } = "header-campaign-select";
 
-    [Parameter] public bool ShowConnectionState { get; set; } = true;
+    [Parameter]
+    public EventCallback<ChangeEventArgs> CampaignSelectionChanged { get; set; }
 
-    [Parameter] public string ConnectionStateLabel { get; set; } = "Offline fallback";
+    [Parameter]
+    public bool ShowConnectionState { get; set; } = true;
 
-    [Parameter] public string ConnectionStateCssClass { get; set; } = "offline";
+    [Parameter]
+    public string ConnectionStateLabel { get; set; } = "Offline fallback";
 
-    [Parameter] public bool IsMenuOpen { get; set; }
+    [Parameter]
+    public string ConnectionStateCssClass { get; set; } = "offline";
 
-    [Parameter] public string MenuButtonId { get; set; } = "screen-menu-button";
+    [Parameter]
+    public bool IsMenuOpen { get; set; }
 
-    [Parameter] public string MenuId { get; set; } = "screen-menu";
+    [Parameter]
+    public string MenuButtonId { get; set; } = "screen-menu-button";
 
-    [Parameter] public IReadOnlyList<AppHeaderMenuItem> MenuItems { get; set; } = [];
+    [Parameter]
+    public string MenuId { get; set; } = "screen-menu";
 
-    [Parameter] public EventCallback ToggleMenuRequested { get; set; }
+    [Parameter]
+    public IReadOnlyList<AppHeaderMenuItem> MenuItems { get; set; } = [];
 
-    [Parameter] public EventCallback LogoutRequested { get; set; }
+    [Parameter]
+    public EventCallback ToggleMenuRequested { get; set; }
+
+    [Parameter]
+    public string Theme { get; set; } = "light";
+
+    [Parameter]
+    public string ThemeToggleLabel { get; set; } = "☀️";
+
+    [Parameter]
+    public EventCallback ThemeToggleRequested { get; set; }
+
+    [Parameter]
+    public EventCallback LogoutRequested { get; set; }
 }
 
 public sealed class AppHeaderMenuItem

RpgRoller/Components/Pages/Workspace.razor

@@ -28,6 +28,9 @@
             MenuId="workspace-screen-menu"
             MenuItems="HeaderMenuItems"
             ToggleMenuRequested="ToggleScreenMenu"
+            Theme="@State.ThemePreference"
+            ThemeToggleLabel="@State.ThemeToggleLabel"
+            ThemeToggleRequested="Session.ToggleThemePreferenceAsync"
             LogoutRequested="Session.LogoutAsync"/>
 
         @if (ChildContent is not null)

RpgRoller/Components/Pages/WorkspaceSessionCoordinator.cs

@@ -1,25 +1,10 @@
-using Microsoft.JSInterop;
+using Microsoft.JSInterop;
 using RpgRoller.Contracts;
+using RpgRoller.Domain;
 
 namespace RpgRoller.Components.Pages;
 
-public sealed class WorkspaceSessionCoordinator(
+public sealed class WorkspaceSessionCoordinator(WorkspaceState state, WorkspaceFeedbackService feedback, IJSRuntime js, RpgRollerApiClient apiClient, WorkspaceQueryService workspaceQuery, Func<bool> isAdminRoute, Func<Task> redirectToPlayAsync, Func<Guid?, Task> reloadCampaignsAsync, Func<Task> reloadCharacterCampaignOptionsAsync, Func<Task> refreshCampaignScopeAsync, Func<Task> requestRefreshAsync, Func<Task> syncStateEventsAsync, Func<Task> stopStateEventsAsync, Func<Task> ensureAdminUsersLoadedAsync, Action resetCampaignLogDetailState, Func<string?, Task> onLoggedOutAsync)
-    WorkspaceState state,
-    WorkspaceFeedbackService feedback,
-    IJSRuntime js,
-    RpgRollerApiClient apiClient,
-    WorkspaceQueryService workspaceQuery,
-    Func<bool> isAdminRoute,
-    Func<Task> redirectToPlayAsync,
-    Func<Guid?, Task> reloadCampaignsAsync,
-    Func<Task> reloadCharacterCampaignOptionsAsync,
-    Func<Task> refreshCampaignScopeAsync,
-    Func<Task> requestRefreshAsync,
-    Func<Task> syncStateEventsAsync,
-    Func<Task> stopStateEventsAsync,
-    Func<Task> ensureAdminUsersLoadedAsync,
-    Action resetCampaignLogDetailState,
-    Func<string?, Task> onLoggedOutAsync)
 {
     public async Task InitializeAsync()
     {
@@ -27,8 +12,7 @@ public sealed class WorkspaceSessionCoordinator(
         if (string.Equals(storedPanel, "log", StringComparison.OrdinalIgnoreCase))
             state.MobilePanel = "log";
 
-        var storedRollVisibility =
+        var storedRollVisibility = await js.InvokeAsync<string?>("rpgRollerApi.getSessionValue", RollVisibilitySessionKey);
-            await js.InvokeAsync<string?>("rpgRollerApi.getSessionValue", RollVisibilitySessionKey);
         state.RollVisibility = NormalizeRollVisibility(storedRollVisibility);
 
         Guid? preferredCampaignId = null;
@@ -101,6 +85,33 @@ public sealed class WorkspaceSessionCoordinator(
         await requestRefreshAsync();
     }
 
+    public async Task ToggleThemePreferenceAsync()
+    {
+        if (state.User is null || state.IsMutating)
+            return;
+
+        var previousTheme = state.ThemePreference;
+        var nextTheme = state.NextThemePreference;
+        state.ThemePreference = nextTheme;
+        await js.InvokeVoidAsync("rpgRollerApi.applyTheme", nextTheme);
+        await requestRefreshAsync();
+
+        try
+        {
+            state.User = await apiClient.RequestAsync<UserSummary>("PUT", "/api/me/theme", new UpdateThemePreferenceRequest(nextTheme));
+            state.ThemePreference = NormalizeThemePreference(state.User.ThemePreference);
+            await js.InvokeVoidAsync("rpgRollerApi.applyTheme", state.ThemePreference);
+        }
+        catch (ApiRequestException ex)
+        {
+            state.ThemePreference = previousTheme;
+            await js.InvokeVoidAsync("rpgRollerApi.applyTheme", previousTheme);
+            feedback.SetStatus(ex.Message, true);
+        }
+
+        await requestRefreshAsync();
+    }
+
     public void ClearAuthenticatedState()
     {
         state.User = null;
@@ -117,6 +128,7 @@ public sealed class WorkspaceSessionCoordinator(
         state.SelectedCharacterId = null;
         state.LastRoll = null;
         state.KnownUsernames = [];
+        state.ThemePreference = ThemePreferences.Light;
         state.ShowCreateCharacterModal = false;
         state.ShowEditCharacterModal = false;
         state.CanEditCharacterOwner = false;
@@ -161,6 +173,7 @@ public sealed class WorkspaceSessionCoordinator(
 
         state.User = me.User;
         state.ActiveCharacterId = me.ActiveCharacterId;
+        await EnsureThemePreferenceAsync();
         if (!await EnsureRouteAccessAsync())
             return true;
 
@@ -211,6 +224,38 @@ public sealed class WorkspaceSessionCoordinator(
         return string.Equals(visibility, "private", StringComparison.OrdinalIgnoreCase) ? "private" : "public";
     }
 
+    private async Task EnsureThemePreferenceAsync()
+    {
+        if (state.User is null)
+            return;
+
+        var themePreference = state.User.ThemePreference;
+        if (ThemePreferences.IsSupported(themePreference))
+        {
+            state.ThemePreference = ThemePreferences.Normalize(themePreference!);
+            await js.InvokeVoidAsync("rpgRollerApi.applyTheme", state.ThemePreference);
+            return;
+        }
+
+        var systemThemePreference = await js.InvokeAsync<string>("rpgRollerApi.getSystemTheme");
+        state.ThemePreference = NormalizeThemePreference(systemThemePreference);
+        await js.InvokeVoidAsync("rpgRollerApi.applyTheme", state.ThemePreference);
+
+        try
+        {
+            state.User = await apiClient.RequestAsync<UserSummary>("PUT", "/api/me/theme", new UpdateThemePreferenceRequest(state.ThemePreference));
+        }
+        catch (ApiRequestException ex)
+        {
+            feedback.SetStatus(ex.Message, true);
+        }
+    }
+
+    private static string NormalizeThemePreference(string? themePreference)
+    {
+        return ThemePreferences.IsSupported(themePreference) ? ThemePreferences.Normalize(themePreference!) : ThemePreferences.Light;
+    }
+
     private const string CampaignSessionKey = "campaign";
     private const string MobilePanelSessionKey = "play-panel";
     private const string RollVisibilitySessionKey = "roll-visibility";

RpgRoller/Components/Pages/WorkspaceState.cs

@@ -17,9 +17,7 @@ public sealed class WorkspaceState
         if (ownerUserId == SelectedCampaign.Gm.Id)
             return $"{SelectedCampaign.Gm.DisplayName} (GM)";
 
-        var ownerDisplayName = SelectedCampaign.Characters.Where(character => character.OwnerUserId == ownerUserId)
+        var ownerDisplayName = SelectedCampaign.Characters.Where(character => character.OwnerUserId == ownerUserId).Select(character => character.OwnerDisplayName).FirstOrDefault(displayName => !string.IsNullOrWhiteSpace(displayName));
-            .Select(character => character.OwnerDisplayName)
-            .FirstOrDefault(displayName => !string.IsNullOrWhiteSpace(displayName));
 
         return string.IsNullOrWhiteSpace(ownerDisplayName) ? "Unknown owner" : ownerDisplayName;
     }
@@ -28,10 +26,8 @@ public sealed class WorkspaceState
     {
         if (!string.Equals(SelectedCampaign?.RulesetId, "d6", StringComparison.OrdinalIgnoreCase))
         {
-            if (string.Equals(SelectedCampaign?.RulesetId, RulesetFormHelpers.RulesetIds.Rolemaster,
+            if (string.Equals(SelectedCampaign?.RulesetId, RulesetFormHelpers.RulesetIds.Rolemaster, StringComparison.OrdinalIgnoreCase))
-                    StringComparison.OrdinalIgnoreCase))
+                return RulesetFormHelpers.DescribeRolemasterExpression(skill.DiceRollDefinition, skill.FumbleRange, skill.RolemasterAutoRetry);
-                return RulesetFormHelpers.DescribeRolemasterExpression(skill.DiceRollDefinition, skill.FumbleRange,
-                    skill.RolemasterAutoRetry);
 
             return skill.DiceRollDefinition;
         }
@@ -55,6 +51,7 @@ public sealed class WorkspaceState
     public RollResult? LastRoll { get; set; }
     public List<string> KnownUsernames { get; set; } = [];
     public string RollVisibility { get; set; } = "public";
+    public string ThemePreference { get; set; } = ThemePreferences.Light;
 
     public bool IsMutating { get; set; }
     public bool IsCampaignDataLoading { get; set; }
@@ -102,17 +99,14 @@ public sealed class WorkspaceState
                 return null;
 
             if (User is null)
-                return new(SelectedCampaign.Id, SelectedCampaign.Name, SelectedCampaign.RulesetId, SelectedCampaign.Gm,
+                return new(SelectedCampaign.Id, SelectedCampaign.Name, SelectedCampaign.RulesetId, SelectedCampaign.Gm, []);
-                    []);
 
             if (IsCurrentUserGm)
                 return SelectedCampaign;
 
-            var ownedCharacters = SelectedCampaign.Characters.Where(character => character.OwnerUserId == User.Id)
+            var ownedCharacters = SelectedCampaign.Characters.Where(character => character.OwnerUserId == User.Id).ToArray();
-                .ToArray();
 
-            return new(SelectedCampaign.Id, SelectedCampaign.Name, SelectedCampaign.RulesetId, SelectedCampaign.Gm,
+            return new(SelectedCampaign.Id, SelectedCampaign.Name, SelectedCampaign.RulesetId, SelectedCampaign.Gm, ownedCharacters);
-                ownedCharacters);
         }
     }
 
@@ -126,18 +120,14 @@ public sealed class WorkspaceState
 
             if (SelectedCharacterId.HasValue)
             {
-                var selectedCharacter =
+                var selectedCharacter = playSelectedCampaign.Characters.FirstOrDefault(character => character.Id == SelectedCharacterId.Value);
-                    playSelectedCampaign.Characters.FirstOrDefault(character =>
-                        character.Id == SelectedCharacterId.Value);
                 if (selectedCharacter is not null)
                     return selectedCharacter;
             }
 
             if (ActiveCharacterId.HasValue)
             {
-                var activeCharacter =
+                var activeCharacter = playSelectedCampaign.Characters.FirstOrDefault(character => character.Id == ActiveCharacterId.Value);
-                    playSelectedCampaign.Characters.FirstOrDefault(character =>
-                        character.Id == ActiveCharacterId.Value);
                 if (activeCharacter is not null)
                     return activeCharacter;
             }
@@ -181,4 +171,9 @@ public sealed class WorkspaceState
         "reconnecting" => "warn",
         _              => "offline"
     };
+
+    public string ThemeToggleLabel => ThemePreference == ThemePreferences.Dark ? "⏾" : "☀️";
+
+    public string NextThemePreference =>
+        ThemePreference == ThemePreferences.Dark ? ThemePreferences.Light : ThemePreferences.Dark;
 }

RpgRoller/Contracts/ApiContracts.cs

@@ -1,4 +1,4 @@
-using System.Text.Json.Serialization;
+using System.Text.Json.Serialization;
 
 namespace RpgRoller.Contracts;
 
@@ -10,10 +10,12 @@ public sealed record RegisterRequest(string Username, string Password, string Di
 
 public sealed record LoginRequest(string Username, string Password);
 
-public sealed record UserSummary(Guid Id, string Username, string DisplayName, IReadOnlyList<string> Roles);
+public sealed record UserSummary(Guid Id, string Username, string DisplayName, IReadOnlyList<string> Roles, string? ThemePreference = null);
 
 public sealed record MeResponse(UserSummary User, Guid? ActiveCharacterId, Guid? CurrentCampaignId);
 
+public sealed record UpdateThemePreferenceRequest(string ThemePreference);
+
 public sealed record AdminUserSummary(Guid Id, string Username, string DisplayName, IReadOnlyList<string> Roles);
 
 public sealed record UpdateUserRolesRequest(IReadOnlyList<string> Roles);

RpgRoller/Contracts/RpgRollerJsonSerializerContext.cs

@@ -1,4 +1,4 @@
-using System.Text.Json;
+using System.Text.Json;
 using System.Text.Json.Serialization;
 
 namespace RpgRoller.Contracts;
@@ -52,6 +52,7 @@ namespace RpgRoller.Contracts;
 [JsonSerializable(typeof(UpdateCharacterRequest))]
 [JsonSerializable(typeof(UpdateSkillGroupRequest))]
 [JsonSerializable(typeof(UpdateSkillRequest))]
+[JsonSerializable(typeof(UpdateThemePreferenceRequest))]
 [JsonSerializable(typeof(UpdateUserRolesRequest))]
 [JsonSerializable(typeof(UserSummary))]
 public partial class RpgRollerJsonSerializerContext : JsonSerializerContext

RpgRoller/Data/RpgRollerDbContext.cs

@@ -1,4 +1,4 @@
-using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore;
 using RpgRoller.Domain;
 
 namespace RpgRoller.Data;
@@ -15,6 +15,7 @@ public sealed class RpgRollerDbContext(DbContextOptions<RpgRollerDbContext> opti
             entity.Property(x => x.PasswordHash).IsRequired();
             entity.Property(x => x.DisplayName).IsRequired().HasMaxLength(128);
             entity.Property(x => x.Roles).IsRequired().HasMaxLength(256);
+            entity.Property(x => x.ThemePreference).IsRequired(false).HasMaxLength(16);
             entity.HasIndex(x => x.UsernameNormalized).IsUnique();
         });
 

RpgRoller/Domain/GameModels.cs

@@ -1,4 +1,4 @@
-namespace RpgRoller.Domain;
+namespace RpgRoller.Domain;
 
 public enum RulesetKind
 {
@@ -22,6 +22,7 @@ public sealed class UserAccount
     public required string DisplayName { get; set; }
     public required string Roles { get; set; }
     public Guid? ActiveCharacterId { get; set; }
+    public string? ThemePreference { get; set; }
 }
 
 public static class UserRoles

RpgRoller/Domain/ThemePreferences.cs

@@ -0,0 +1,17 @@
+namespace RpgRoller.Domain;
+
+public static class ThemePreferences
+{
+    public const string Light = "light";
+    public const string Dark = "dark";
+
+    public static bool IsSupported(string? value)
+    {
+        return string.Equals(value, Light, StringComparison.OrdinalIgnoreCase) || string.Equals(value, Dark, StringComparison.OrdinalIgnoreCase);
+    }
+
+    public static string Normalize(string value)
+    {
+        return string.Equals(value, Dark, StringComparison.OrdinalIgnoreCase) ? Dark : Light;
+    }
+}

RpgRoller/Migrations/20260518183838_AddUserThemePreference.Designer.cs

@@ -0,0 +1,273 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using RpgRoller.Data;
+
+#nullable disable
+
+namespace RpgRoller.Migrations
+{
+    [DbContext(typeof(RpgRollerDbContext))]
+    [Migration("20260518183838_AddUserThemePreference")]
+    partial class AddUserThemePreference
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "10.0.2");
+
+            modelBuilder.Entity("RpgRoller.Domain.Campaign", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("GmUserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Ruleset")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<long>("Version")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("GmUserId");
+
+                    b.ToTable("Campaigns");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.Character", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("CampaignId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("OwnerUserId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CampaignId");
+
+                    b.HasIndex("OwnerUserId");
+
+                    b.ToTable("Characters");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.RollLogEntry", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Breakdown")
+                        .IsRequired()
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("CampaignId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("CharacterId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Dice")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("Result")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<Guid>("RollerUserId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("SkillId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("TimestampUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Visibility")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CampaignId");
+
+                    b.HasIndex("CharacterId");
+
+                    b.HasIndex("RollerUserId");
+
+                    b.HasIndex("SkillId");
+
+                    b.ToTable("RollLogEntries");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.Skill", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("AllowFumble")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<Guid>("CharacterId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("DiceRollDefinition")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int?>("FumbleRange")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("RolemasterAutoRetry")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false);
+
+                    b.Property<Guid?>("SkillGroupId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("WildDice")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CharacterId");
+
+                    b.HasIndex("SkillGroupId");
+
+                    b.ToTable("Skills");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.SkillGroup", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<bool>("AllowFumble")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<Guid>("CharacterId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("DiceRollDefinition")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int?>("FumbleRange")
+                        .HasColumnType("INTEGER");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<int>("WildDice")
+                        .HasColumnType("INTEGER");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CharacterId");
+
+                    b.ToTable("SkillGroups");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.UserAccount", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid?>("ActiveCharacterId")
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("DisplayName")
+                        .IsRequired()
+                        .HasMaxLength(128)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Roles")
+                        .IsRequired()
+                        .HasMaxLength(256)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("ThemePreference")
+                        .HasMaxLength(16)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.Property<string>("UsernameNormalized")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UsernameNormalized")
+                        .IsUnique();
+
+                    b.ToTable("Users");
+                });
+
+            modelBuilder.Entity("RpgRoller.Domain.UserSession", b =>
+                {
+                    b.Property<string>("Token")
+                        .HasMaxLength(64)
+                        .HasColumnType("TEXT");
+
+                    b.Property<DateTimeOffset>("CreatedAtUtc")
+                        .HasColumnType("TEXT");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("TEXT");
+
+                    b.HasKey("Token");
+
+                    b.HasIndex("UserId");
+
+                    b.ToTable("Sessions");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

RpgRoller/Migrations/20260518183838_AddUserThemePreference.cs

@@ -0,0 +1,22 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace RpgRoller.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddUserThemePreference : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<string>(name: "ThemePreference", table: "Users", type: "TEXT", maxLength: 16, nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(name: "ThemePreference", table: "Users");
+        }
+    }
+}

RpgRoller/Migrations/RpgRollerDbContextModelSnapshot.cs

@@ -224,6 +224,10 @@ namespace RpgRoller.Migrations
                         .HasMaxLength(256)
                         .HasColumnType("TEXT");
 
+                    b.Property<string>("ThemePreference")
+                        .HasMaxLength(16)
+                        .HasColumnType("TEXT");
+
                     b.Property<string>("Username")
                         .IsRequired()
                         .HasMaxLength(64)

RpgRoller/Services/GameAuthService.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Identity;
 using RpgRoller.Contracts;
 using RpgRoller.Domain;
 
@@ -32,7 +32,8 @@ public sealed class GameAuthService(GameStateStore stateStore, IPasswordHasher<U
                 DisplayName = displayName.Trim(),
                 PasswordHash = string.Empty,
                 Roles = stateStore.UsersById.Count == 0 ? UserRoles.Admin : string.Empty,
-                ActiveCharacterId = null
+                ActiveCharacterId = null,
+                ThemePreference = null
             };
 
             user.PasswordHash = passwordHasher.HashPassword(user, password);
@@ -112,6 +113,23 @@ public sealed class GameAuthService(GameStateStore stateStore, IPasswordHasher<U
         }
     }
 
+    public ServiceResult<UserSummary> UpdateThemePreference(string sessionToken, string themePreference)
+    {
+        lock (stateStore.Gate)
+        {
+            var user = GameContextResolver.ResolveUserLocked(stateStore, sessionToken);
+            if (user is null)
+                return ServiceResult<UserSummary>.Failure("unauthorized", "You must be logged in.");
+
+            if (!ThemePreferences.IsSupported(themePreference))
+                return ServiceResult<UserSummary>.Failure("invalid_theme_preference", "Theme preference must be light or dark.");
+
+            user.ThemePreference = ThemePreferences.Normalize(themePreference);
+            persistenceService.PersistStateLocked();
+            return ServiceResult<UserSummary>.Success(GameDtoMapper.ToUserSummary(user));
+        }
+    }
+
     private UserSession CreateSession(Guid userId)
     {
         var token = Guid.NewGuid().ToString("N");

RpgRoller/Services/GameDtoMapper.cs

@@ -1,4 +1,4 @@
-using RpgRoller.Contracts;
+using RpgRoller.Contracts;
 using RpgRoller.Domain;
 
 namespace RpgRoller.Services;
@@ -7,7 +7,7 @@ public static class GameDtoMapper
 {
     public static UserSummary ToUserSummary(UserAccount user)
     {
-        return new(user.Id, user.Username, user.DisplayName, RoleSerializer.Parse(user.Roles));
+        return new(user.Id, user.Username, user.DisplayName, RoleSerializer.Parse(user.Roles), user.ThemePreference);
     }
 
     public static AdminUserSummary ToAdminUserSummary(UserAccount user)

RpgRoller/Services/GamePersistenceService.cs

@@ -1,4 +1,4 @@
-using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore;
 using RpgRoller.Data;
 using RpgRoller.Domain;
 
@@ -40,7 +40,8 @@ public sealed class GamePersistenceService(IDbContextFactory<RpgRollerDbContext>
                     PasswordHash = user.PasswordHash,
                     DisplayName = user.DisplayName,
                     Roles = string.IsNullOrWhiteSpace(user.Roles) ? string.Empty : RoleSerializer.Serialize(RoleSerializer.Parse(user.Roles)),
-                    ActiveCharacterId = user.ActiveCharacterId
+                    ActiveCharacterId = user.ActiveCharacterId,
+                    ThemePreference = string.IsNullOrWhiteSpace(user.ThemePreference) ? null : ThemePreferences.Normalize(user.ThemePreference)
                 };
                 stateStore.UsersById[storedUser.Id] = storedUser;
                 stateStore.UserIdsByUsername[normalizedUsername] = storedUser.Id;

RpgRoller/Services/GameService.cs

@@ -1,4 +1,4 @@
-using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Identity;
 using Microsoft.EntityFrameworkCore;
 using RpgRoller.Contracts;
 using RpgRoller.Data;
@@ -55,6 +55,11 @@ public sealed class GameService : IGameService
         return m_AuthService.GetMe(sessionToken);
     }
 
+    public ServiceResult<UserSummary> UpdateThemePreference(string sessionToken, string themePreference)
+    {
+        return m_AuthService.UpdateThemePreference(sessionToken, themePreference);
+    }
+
     public ServiceResult<CampaignSummary> CreateCampaign(string sessionToken, string name, string rulesetId)
     {
         return m_CampaignService.CreateCampaign(sessionToken, name, rulesetId);

RpgRoller/Services/GameStateCloneFactory.cs

@@ -1,4 +1,4 @@
-using RpgRoller.Domain;
+using RpgRoller.Domain;
 
 namespace RpgRoller.Services;
 
@@ -14,7 +14,8 @@ public static class GameStateCloneFactory
             PasswordHash = user.PasswordHash,
             DisplayName = user.DisplayName,
             Roles = user.Roles,
-            ActiveCharacterId = user.ActiveCharacterId
+            ActiveCharacterId = user.ActiveCharacterId,
+            ThemePreference = user.ThemePreference
         };
     }
 

RpgRoller/Services/IGameService.cs

@@ -1,4 +1,4 @@
-using RpgRoller.Contracts;
+using RpgRoller.Contracts;
 
 namespace RpgRoller.Services;
 
@@ -11,6 +11,7 @@ public interface IGameService
     void Logout(string sessionToken);
     UserSummary? GetUserBySession(string sessionToken);
     ServiceResult<MeResponse> GetMe(string sessionToken);
+    ServiceResult<UserSummary> UpdateThemePreference(string sessionToken, string themePreference);
 
     ServiceResult<CampaignSummary> CreateCampaign(string sessionToken, string name, string rulesetId);
     ServiceResult<IReadOnlyList<CampaignSummary>> GetCampaigns(string sessionToken);

RpgRoller/wwwroot/js/rpgroller-api.js

@@ -1,4 +1,4 @@
-window.rpgRollerApi = (() => {
+window.rpgRollerApi = (() => {
     const sessionPrefix = "rpgroller.";
     const stateStream = {
         source: null,
@@ -22,6 +22,18 @@ window.rpgRollerApi = (() => {
         return new URL(relativeUrl, document.baseURI).toString();
     }
 
+    function normalizeTheme(theme) {
+        return theme === "dark" ? "dark" : "light";
+    }
+
+    function getSystemTheme() {
+        return window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+    }
+
+    function applyTheme(theme) {
+        document.documentElement.dataset.theme = normalizeTheme(theme);
+    }
+
     function clearReconnectTimer() {
         if (stateStream.reconnectTimer) {
             clearTimeout(stateStream.reconnectTimer);
@@ -385,6 +397,8 @@ window.rpgRollerApi = (() => {
 
     return {
         request,
+        applyTheme,
+        getSystemTheme,
         getSessionValue,
         setSessionValue,
         startStateEvents,

RpgRoller/wwwroot/styles.css

@@ -1,4 +1,5 @@
 :root {
+    color-scheme: light;
     --bg-top: #f7f0d8;
     --bg-bottom: #ecdfc4;
     --button-hover: #dccfb4;
@@ -14,6 +15,147 @@
     --public: #2d6645;
     --private-self: #4f3a8f;
     --private-gm: #915119;
+    --page-background: url("/images/light.png");
+    --card-strong: #fff8ea;
+    --accent-dark: #2f4f34;
+    --accent-2-hover: #6b2419;
+    --header-bg: linear-gradient(120deg, #f1e4c9, #efe0bf);
+    --input-bg: #fffdf5;
+    --input-border: #8e7b57;
+    --button-text: #f8f7ef;
+    --switch-active-text: #fff9ef;
+    --tab-active-bg: linear-gradient(145deg, #e9d4a4, #d7b672);
+    --tab-active-border: #9e7328;
+    --section-border: #a89066;
+    --skill-group-bg: #f8f0de;
+    --chip-border: #decbb7;
+    --menu-shadow: rgba(34, 24, 9, 0.2);
+    --die-border: #2a2418;
+    --die-bg: #ffffff;
+    --die-text: #1f1a13;
+    --die-wild: #c79913;
+    --die-crit-bg: #d8ffc2;
+    --die-crit-text: #18490f;
+    --die-fumble-bg: #ffb5a8;
+    --die-fumble-text: #661110;
+    --die-added-bg: #dbffdf;
+    --die-added-text: #206029;
+    --die-removed-bg: #fde0dd;
+    --die-removed-text: #7f5f55;
+    --die-neutral-bg: #f8f1df;
+    --die-neutral-text: #3f2f12;
+    --die-open-high-bg: #dff6df;
+    --die-open-high-text: #1d5b26;
+    --die-open-high-border: #2a7c39;
+    --die-open-low-bg: #ffe1dc;
+    --die-open-low-text: #8a2217;
+    --die-open-low-border: #b74334;
+    --success-bg: #e8f7e8;
+    --success-border: #78a978;
+    --success-text: #1f5425;
+    --error-bg: #ffe9e5;
+    --error-border: #bb6e62;
+    --error-text: #7f2015;
+    --rare-bg: #fff1c7;
+    --rare-border: #b48b34;
+    --rare-text: #6d4c05;
+    --active-bg: #f6d28d;
+    --active-border: #8f5f12;
+    --active-text: #5d3808;
+    --skeleton-bg: linear-gradient(90deg, #dfd2b7, #efe3c9, #dfd2b7);
+    --health-bg: #fff2db;
+    --health-border: #b77a29;
+    --modal-overlay: rgba(35, 25, 9, 0.55);
+    --mobile-nav-bg: rgba(241, 228, 201, 0.96);
+    --toast-shadow: rgba(34, 24, 9, 0.22);
+    --surface-mix: #ffffff;
+    --transparent-mix: transparent;
+    --custom-roll-error-bg: #fff0ee;
+    --custom-roll-error-border: #6b2015;
+    --custom-roll-error-shadow: rgba(181, 58, 35, 0.12);
+    --entry-shadow: rgba(60, 41, 12, 0.07);
+    --entry-shadow-hover: rgba(60, 41, 12, 0.11);
+    --fresh-shadow: rgba(199, 153, 19, 0.16);
+}
+
+:root[data-theme="dark"] {
+    color-scheme: dark;
+    --bg-top: #060b13;
+    --bg-bottom: #0c1726;
+    --button-hover: rgba(62, 89, 123, 0.72);
+    --card: rgba(8, 15, 26, 0.84);
+    --card-border: #37516c;
+    --text: #edf5ff;
+    --muted: #adc1d6;
+    --accent: #5aa0cf;
+    --accent-2: #f0b35a;
+    --warn: #f4c35f;
+    --danger: #ff8b7a;
+    --focus: #91d5ff;
+    --public: #78d08f;
+    --private-self: #b9a0ff;
+    --private-gm: #f0b16c;
+    --page-background: url("/images/dark.png");
+    --card-strong: rgba(13, 24, 39, 0.96);
+    --accent-dark: #2d638f;
+    --accent-2-hover: #ffd085;
+    --header-bg: linear-gradient(120deg, rgba(10, 18, 31, 0.94), rgba(17, 31, 48, 0.9));
+    --input-bg: rgba(7, 14, 24, 0.92);
+    --input-border: #52708f;
+    --button-text: #f3f8ff;
+    --switch-active-text: #0b1420;
+    --tab-active-bg: linear-gradient(145deg, #244967, #17324d);
+    --tab-active-border: #6ca6d0;
+    --section-border: #486986;
+    --skill-group-bg: rgba(19, 34, 52, 0.72);
+    --chip-border: #415f7b;
+    --menu-shadow: rgba(0, 0, 0, 0.42);
+    --die-border: #9cb8d3;
+    --die-bg: #0f1c2d;
+    --die-text: #edf5ff;
+    --die-wild: #ffd770;
+    --die-crit-bg: #163f2a;
+    --die-crit-text: #a5f0b5;
+    --die-fumble-bg: #4b1c20;
+    --die-fumble-text: #ffc0b8;
+    --die-added-bg: #163f2a;
+    --die-added-text: #a5f0b5;
+    --die-removed-bg: #3b2630;
+    --die-removed-text: #e0abb7;
+    --die-neutral-bg: #14283e;
+    --die-neutral-text: #e5f1ff;
+    --die-open-high-bg: #133b2b;
+    --die-open-high-text: #a5f0b5;
+    --die-open-high-border: #64c783;
+    --die-open-low-bg: #482025;
+    --die-open-low-text: #ffc0b8;
+    --die-open-low-border: #ff8b7a;
+    --success-bg: #173b29;
+    --success-border: #66bd7f;
+    --success-text: #b6f1c3;
+    --error-bg: #452126;
+    --error-border: #d46b62;
+    --error-text: #ffc2ba;
+    --rare-bg: #3d3218;
+    --rare-border: #cfae52;
+    --rare-text: #ffe09a;
+    --active-bg: #4a3514;
+    --active-border: #e0b35d;
+    --active-text: #ffe1a3;
+    --skeleton-bg: linear-gradient(90deg, #172438, #263b54, #172438);
+    --health-bg: #3a2d19;
+    --health-border: #d09b4c;
+    --modal-overlay: rgba(1, 6, 13, 0.74);
+    --mobile-nav-bg: rgba(10, 18, 31, 0.96);
+    --toast-shadow: rgba(0, 0, 0, 0.42);
+    --surface-mix: #000000;
+    --transparent-mix: transparent;
+    --custom-roll-error-bg: #371c21;
+    --custom-roll-error-border: #ffc0b8;
+    --custom-roll-error-shadow: rgba(255, 139, 122, 0.18);
+    --entry-shadow: rgba(0, 0, 0, 0.24);
+    --entry-shadow-hover: rgba(0, 0, 0, 0.34);
+    --fresh-shadow: rgba(255, 215, 112, 0.2);
 }
 
 * {
@@ -28,7 +170,7 @@ body {
 }
 
 html {
-    background-image: url("/images/rpg.png");
+    background-image: var(--page-background);
     background-position: center;
     background-repeat: no-repeat;
     background-size: cover;
@@ -100,7 +242,7 @@ h3 {
     top: 0;
     z-index: 10;
     display: flex;
-    background: linear-gradient(120deg, #f1e4c9, #efe0bf);
+    background: var(--header-bg);
     border: 1px solid var(--card-border);
     border-radius: 0.8rem;
     padding: 0.5rem 0.7rem;
@@ -209,19 +351,19 @@ select,
 button {
     font: inherit;
     border-radius: 0.45rem;
-    border: 1px solid #8e7b57;
+    border: 1px solid var(--input-border);
     padding: 0.55rem 0.65rem;
 }
 
 input,
 select {
-    background: #fffdf5;
+    background: var(--input-bg);
     color: var(--text);
 }
 
 button {
-    background: linear-gradient(180deg, var(--accent), #2f4f34);
+    background: linear-gradient(180deg, var(--accent), var(--accent-dark));
-    color: #f8f7ef;
+    color: var(--button-text);
     border-color: transparent;
     cursor: pointer;
 }
@@ -229,19 +371,19 @@ button {
 button.ghost {
     background: transparent;
     color: var(--text);
-    border-color: #8e7b57;
+    border-color: var(--input-border);
 }
 
 button.switch {
     background: transparent;
     color: var(--text);
-    border-color: #8e7b57;
+    border-color: var(--input-border);
 }
 
 button.switch.active {
     background: var(--accent-2);
     border-color: var(--accent-2);
-    color: #fff9ef;
+    color: var(--switch-active-text);
 }
 
 button:disabled {
@@ -327,12 +469,12 @@ select:focus-visible {
     white-space: nowrap;
     background: transparent;
     color: var(--text);
-    border-color: #8e7b57;
+    border-color: var(--input-border);
 }
 
 .icon-tab.active {
-    background: linear-gradient(145deg, #e9d4a4, #d7b672);
+    background: var(--tab-active-bg);
-    border-color: #9e7328;
+    border-color: var(--tab-active-border);
 }
 
 .icon-tab-glyph {
@@ -342,7 +484,7 @@ select:focus-visible {
     align-items: center;
     justify-content: center;
     border-radius: 50%;
-    border: 1px solid #8e7b57;
+    border: 1px solid var(--input-border);
     font-weight: 700;
     font-size: 0.72rem;
 }
@@ -353,7 +495,7 @@ select:focus-visible {
 }
 
 .skills-section {
-    border: 1px dashed #a89066;
+    border: 1px dashed var(--section-border);
     border-radius: 0.65rem;
     padding: 0.55rem;
     display: flex;
@@ -414,7 +556,7 @@ select:focus-visible {
     display: flex;
     align-items: center;
     justify-content: space-between;
-    background-color: #f8f0de;
+    background-color: var(--skill-group-bg);
     padding: 0.1rem;
     border-top: 1px solid var(--card-border);
     gap: 0.5rem;
@@ -457,11 +599,11 @@ select:focus-visible {
     border-radius: 999px;
     background: transparent;
     color: var(--text);
-    border-color: #decbb7;
+    border-color: var(--chip-border);
 }
 
 .chip-button:hover {
-    border-color: #8e7b57;
+    border-color: var(--input-border);
     background: var(--button-hover);
 }
 
@@ -469,13 +611,13 @@ select:focus-visible {
     grid-template-columns: auto 1fr;
     align-items: center;
     justify-items: start;
-    background: #00000000;
+    background: transparent;
 }
 
 .skill-create-icon {
     width: 1.45rem;
     height: 1.45rem;
-    border: 1px solid #8e7b57;
+    border: 1px solid var(--input-border);
     border-radius: 999px;
     display: inline-flex;
     align-items: center;
@@ -520,7 +662,7 @@ select:focus-visible {
 .menu-toggle {
     background: transparent;
     color: var(--text);
-    border-color: #8e7b57;
+    border-color: var(--input-border);
     display: inline-flex;
     gap: 0.4rem;
     align-items: center;
@@ -537,12 +679,12 @@ select:focus-visible {
     z-index: 40;
     min-width: 14.5rem;
     padding: 0.35rem;
-    background: #fff8ea;
+    background: var(--card-strong);
     border: 1px solid var(--card-border);
     border-radius: 0.55rem;
     display: grid;
     gap: 0.3rem;
-    box-shadow: 0 8px 16px rgba(34, 24, 9, 0.2);
+    box-shadow: 0 8px 16px var(--menu-shadow);
 }
 
 .menu-item {
@@ -550,12 +692,12 @@ select:focus-visible {
     text-align: left;
     background: transparent;
     color: var(--text);
-    border-color: #8e7b57;
+    border-color: var(--input-border);
 }
 
 .menu-item.active {
-    background: #ecd8ae;
+    background: var(--button-hover);
-    border-color: #9a7f43;
+    border-color: var(--tab-active-border);
 }
 
 .logout-link {
@@ -566,7 +708,7 @@ select:focus-visible {
 }
 
 .logout-link:hover {
-    color: #6b2419;
+    color: var(--accent-2-hover);
 }
 
 .logout-link:focus-visible {
@@ -574,6 +716,22 @@ select:focus-visible {
     outline-offset: 2px;
 }
 
+.theme-toggle {
+    width: 2.25rem;
+    height: 2.25rem;
+    display: inline-flex;
+    align-items: center;
+    justify-content: center;
+    padding: 0;
+    background: transparent;
+    color: var(--text);
+    border-color: var(--input-border);
+}
+
+.theme-toggle:hover {
+    background: var(--button-hover);
+}
+
 .roll-total {
     font-size: 1.8rem;
     font-weight: 800;
@@ -597,10 +755,10 @@ select:focus-visible {
     min-width: 2.1rem;
     height: 2.1rem;
     padding: 0.2rem 0.45rem 0;
-    border: 2px solid #2a2418;
+    border: 2px solid var(--die-border);
     border-radius: 0.45rem;
-    background: #ffffff;
+    background: var(--die-bg);
-    color: #1f1a13;
+    color: var(--die-text);
     font-size: 2rem;
     line-height: 1;
     font-variant-numeric: tabular-nums;
@@ -608,27 +766,27 @@ select:focus-visible {
 
 .die-chip.wild {
     border-width: 3px;
-    border-color: #c79913;
+    border-color: var(--die-wild);
 }
 
 .die-chip.crit {
-    background: #d8ffc2;
+    background: var(--die-crit-bg);
-    color: #18490f;
+    color: var(--die-crit-text);
 }
 
 .die-chip.fumble {
-    background: #ffb5a8;
+    background: var(--die-fumble-bg);
-    color: #661110;
+    color: var(--die-fumble-text);
 }
 
 .die-chip.added {
-    background: #dbffdf;
+    background: var(--die-added-bg);
-    color: #206029;
+    color: var(--die-added-text);
 }
 
 .die-chip.removed {
-    background: #fde0dd;
+    background: var(--die-removed-bg);
-    color: #7f5f55;
+    color: var(--die-removed-text);
     border-style: dashed;
 }
 
@@ -646,20 +804,20 @@ select:focus-visible {
 .die-chip.rolemaster-initiative,
 .die-chip.rolemaster-percentile,
 .die-chip.rolemaster-open-ended-initial {
-    background: #f8f1df;
+    background: var(--die-neutral-bg);
-    color: #3f2f12;
+    color: var(--die-neutral-text);
 }
 
 .die-chip.rolemaster-open-ended-high {
-    background: #dff6df;
+    background: var(--die-open-high-bg);
-    color: #1d5b26;
+    color: var(--die-open-high-text);
-    border-color: #2a7c39;
+    border-color: var(--die-open-high-border);
 }
 
 .die-chip.rolemaster-open-ended-low-subtract {
-    background: #ffe1dc;
+    background: var(--die-open-low-bg);
-    color: #8a2217;
+    color: var(--die-open-low-text);
-    border-color: #b74334;
+    border-color: var(--die-open-low-border);
 }
 
 .empty,
@@ -676,11 +834,11 @@ select:focus-visible {
 }
 
 .custom-roll-panel {
-    border-top: 1px solid color-mix(in srgb, var(--card-border) 72%, #ffffff 28%);
+    border-top: 1px solid color-mix(in srgb, var(--card-border) 72%, var(--surface-mix) 28%);
-    background: color-mix(in srgb, var(--card) 88%, #ffffff 12%);
+    background: color-mix(in srgb, var(--card) 88%, var(--surface-mix) 12%);
     border-radius: 0.95rem;
     padding: 0.85rem 0.9rem 0.9rem;
-    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.45);
+    box-shadow: inset 0 1px 0 color-mix(in srgb, var(--surface-mix) 45%, transparent 55%);
 }
 
 .custom-roll-composer {
@@ -712,14 +870,14 @@ select:focus-visible {
     min-width: 0;
     padding: 0.72rem 0.9rem;
     border-radius: 999px;
-    border: 1px solid color-mix(in srgb, var(--card-border) 78%, #ffffff 22%);
+    border: 1px solid color-mix(in srgb, var(--card-border) 78%, var(--surface-mix) 22%);
-    background: color-mix(in srgb, var(--card) 90%, #ffffff 10%);
+    background: color-mix(in srgb, var(--card) 90%, var(--surface-mix) 10%);
-    box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.6);
+    box-shadow: inset 0 1px 0 color-mix(in srgb, var(--surface-mix) 60%, transparent 40%);
     transition: border-color 180ms ease, box-shadow 180ms ease, background-color 180ms ease;
 }
 
 .custom-roll-input::placeholder {
-    color: color-mix(in srgb, var(--muted) 80%, #ffffff 20%);
+    color: color-mix(in srgb, var(--muted) 80%, var(--surface-mix) 20%);
 }
 
 .custom-roll-input:hover:not(:disabled) {
@@ -727,9 +885,9 @@ select:focus-visible {
 }
 
 .custom-roll-input.error {
-    border-color: color-mix(in srgb, var(--danger) 74%, #6b2015 26%);
+    border-color: color-mix(in srgb, var(--danger) 74%, var(--custom-roll-error-border) 26%);
-    background: color-mix(in srgb, #fff0ee 84%, var(--card) 16%);
+    background: color-mix(in srgb, var(--custom-roll-error-bg) 84%, var(--card) 16%);
-    box-shadow: 0 0 0 3px rgba(181, 58, 35, 0.12);
+    box-shadow: 0 0 0 3px var(--custom-roll-error-shadow);
 }
 
 .custom-roll-composer-row button {
@@ -739,11 +897,11 @@ select:focus-visible {
 }
 
 .log-entry {
-    border: 1px solid color-mix(in srgb, var(--card-border) 84%, #ffffff 16%);
+    border: 1px solid color-mix(in srgb, var(--card-border) 84%, var(--surface-mix) 16%);
     border-radius: 0.85rem;
-    background: color-mix(in srgb, var(--card) 96%, #ffffff 4%);
+    background: color-mix(in srgb, var(--card) 96%, var(--surface-mix) 4%);
     overflow: hidden;
-    box-shadow: 0 0.45rem 1.2rem rgba(60, 41, 12, 0.07);
+    box-shadow: 0 0.45rem 1.2rem var(--entry-shadow);
     transition: border-color 180ms ease, box-shadow 180ms ease, transform 180ms ease;
 }
 
@@ -762,23 +920,23 @@ select:focus-visible {
 
 .log-entry:hover {
     border-color: color-mix(in srgb, var(--accent) 28%, var(--card-border) 72%);
-    box-shadow: 0 0.7rem 1.55rem rgba(60, 41, 12, 0.11);
+    box-shadow: 0 0.7rem 1.55rem var(--entry-shadow-hover);
 }
 
 .log-entry.private-self {
-    border-left: 0.35rem solid color-mix(in srgb, var(--private-self) 78%, #ffffff 22%);
+    border-left: 0.35rem solid color-mix(in srgb, var(--private-self) 78%, var(--surface-mix) 22%);
 }
 
 .log-entry.private-gm {
-    border-left: 0.35rem solid color-mix(in srgb, var(--private-gm) 78%, #ffffff 22%);
+    border-left: 0.35rem solid color-mix(in srgb, var(--private-gm) 78%, var(--surface-mix) 22%);
 }
 
 .log-entry.public {
-    border-left: 0.35rem solid color-mix(in srgb, var(--public) 70%, #ffffff 30%);
+    border-left: 0.35rem solid color-mix(in srgb, var(--public) 70%, var(--surface-mix) 30%);
 }
 
 .log-entry.private-generic {
-    border-left: 0.35rem solid color-mix(in srgb, var(--muted) 52%, #ffffff 48%);
+    border-left: 0.35rem solid color-mix(in srgb, var(--muted) 52%, var(--surface-mix) 48%);
 }
 
 .log-entry.expanded {
@@ -786,12 +944,12 @@ select:focus-visible {
 }
 
 .log-entry.fresh {
-    border-color: color-mix(in srgb, #c79913 52%, var(--card-border) 48%);
+    border-color: color-mix(in srgb, var(--die-wild) 52%, var(--card-border) 48%);
-    box-shadow: 0 0.9rem 1.8rem rgba(199, 153, 19, 0.16);
+    box-shadow: 0 0.9rem 1.8rem var(--fresh-shadow);
 }
 
 .log-entry-toggle:hover {
-    background: color-mix(in srgb, var(--card) 84%, #ffffff 16%);
+    background: color-mix(in srgb, var(--card) 84%, var(--surface-mix) 16%);
 }
 
 .log-entry-toggle:focus-visible {
@@ -855,21 +1013,21 @@ select:focus-visible {
 }
 
 .log-event-badge.positive {
-    border-color: #79a85d;
+    border-color: var(--success-border);
-    background: #e7f6da;
+    background: var(--success-bg);
-    color: #235217;
+    color: var(--success-text);
 }
 
 .log-event-badge.danger {
-    border-color: #c56b5a;
+    border-color: var(--error-border);
-    background: #ffe3dc;
+    background: var(--error-bg);
-    color: #7d1f17;
+    color: var(--error-text);
 }
 
 .log-event-badge.rare {
-    border-color: #b48b34;
+    border-color: var(--rare-border);
-    background: #fff1c7;
+    background: var(--rare-bg);
-    color: #6d4c05;
+    color: var(--rare-text);
 }
 
 .log-meta {
@@ -885,7 +1043,7 @@ select:focus-visible {
     margin: 0 0.65rem 0.65rem;
     padding: 0.7rem 0.8rem 0.75rem;
     border-top: 1px solid color-mix(in srgb, var(--card-border) 38%, transparent 62%);
-    background: color-mix(in srgb, #ffffff 42%, var(--card) 58%);
+    background: color-mix(in srgb, var(--surface-mix) 42%, var(--card) 58%);
     border-radius: 0.7rem;
 }
 
@@ -904,31 +1062,31 @@ select:focus-visible {
 }
 
 .badge.active {
-    border-color: #8f5f12;
+    border-color: var(--active-border);
-    background: #f6d28d;
+    background: var(--active-bg);
-    color: #5d3808;
+    color: var(--active-text);
 }
 
 .badge.public {
-    background: color-mix(in srgb, var(--public) 14%, #ffffff 86%);
+    background: color-mix(in srgb, var(--public) 14%, var(--surface-mix) 86%);
     color: var(--public);
     border-color: color-mix(in srgb, var(--public) 34%, transparent 66%);
 }
 
 .badge.private-self {
-    background: color-mix(in srgb, var(--private-self) 12%, #ffffff 88%);
+    background: color-mix(in srgb, var(--private-self) 12%, var(--surface-mix) 88%);
     color: var(--private-self);
     border-color: color-mix(in srgb, var(--private-self) 30%, transparent 70%);
 }
 
 .badge.private-gm {
-    background: color-mix(in srgb, var(--private-gm) 12%, #ffffff 88%);
+    background: color-mix(in srgb, var(--private-gm) 12%, var(--surface-mix) 88%);
     color: var(--private-gm);
     border-color: color-mix(in srgb, var(--private-gm) 30%, transparent 70%);
 }
 
 .badge.private-generic {
-    background: color-mix(in srgb, var(--muted) 12%, #ffffff 88%);
+    background: color-mix(in srgb, var(--muted) 12%, var(--surface-mix) 88%);
     color: var(--muted);
     border-color: color-mix(in srgb, var(--muted) 28%, transparent 72%);
 }
@@ -993,7 +1151,7 @@ select:focus-visible {
 .skeleton-line {
     height: 0.85rem;
     border-radius: 0.4rem;
-    background: linear-gradient(90deg, #dfd2b7, #efe3c9, #dfd2b7);
+    background: var(--skeleton-bg);
     background-size: 220% 100%;
     animation: shimmer 1.1s linear infinite;
 }
@@ -1003,8 +1161,8 @@ select:focus-visible {
 }
 
 .health-banner {
-    border: 1px solid #b77a29;
+    border: 1px solid var(--health-border);
-    background: #fff2db;
+    background: var(--health-bg);
     border-radius: 0.75rem;
     padding: 0.75rem;
     display: flex;
@@ -1026,7 +1184,7 @@ select:focus-visible {
     justify-content: space-between;
     align-items: center;
     gap: 0.5rem;
-    border: 1px solid #b8a37b;
+    border: 1px solid var(--card-border);
     border-radius: 0.55rem;
     padding: 0.5rem;
 }
@@ -1047,9 +1205,9 @@ select:focus-visible {
     gap: 0.45rem;
     align-self: flex-start;
     padding: 0.55rem 0.65rem;
-    border: 1px solid #b39f79;
+    border: 1px solid var(--card-border);
     border-radius: 0.45rem;
-    background: #f9f2e2;
+    background: var(--input-bg);
     color: var(--text);
     font-weight: 700;
     text-decoration: none;
@@ -1069,15 +1227,15 @@ select:focus-visible {
     align-items: center;
     gap: 0.45rem;
     align-self: flex-start;
-    background: #f9f2e2;
+    background: var(--input-bg);
     color: var(--text);
-    border: 1px solid #b39f79;
+    border: 1px solid var(--card-border);
 }
 
 .add-row-icon {
     width: 1.2rem;
     height: 1.2rem;
-    border: 1px solid #8e7b57;
+    border: 1px solid var(--input-border);
     border-radius: 999px;
     display: inline-flex;
     align-items: center;
@@ -1088,7 +1246,7 @@ select:focus-visible {
 .modal-overlay {
     position: fixed;
     inset: 0;
-    background: rgba(35, 25, 9, 0.55);
+    background: var(--modal-overlay);
     display: grid;
     place-items: center;
     z-index: 20;
@@ -1118,7 +1276,7 @@ select:focus-visible {
     padding: 0.55rem;
     display: none;
     gap: 0.45rem;
-    background: rgba(241, 228, 201, 0.96);
+    background: var(--mobile-nav-bg);
     border-top: 1px solid var(--card-border);
 }
 
@@ -1136,7 +1294,7 @@ select:focus-visible {
     border-radius: 0.6rem;
     border: 1px solid;
     padding: 0.55rem 0.7rem;
-    box-shadow: 0 6px 14px rgba(34, 24, 9, 0.22);
+    box-shadow: 0 6px 14px var(--toast-shadow);
     backdrop-filter: blur(4px);
 }
 
@@ -1146,15 +1304,15 @@ select:focus-visible {
 }
 
 .toast.success {
-    background: #e8f7e8;
+    background: var(--success-bg);
-    border-color: #78a978;
+    border-color: var(--success-border);
-    color: #1f5425;
+    color: var(--success-text);
 }
 
 .toast.error {
-    background: #ffe9e5;
+    background: var(--error-bg);
-    border-color: #bb6e62;
+    border-color: var(--error-border);
-    color: #7f2015;
+    color: var(--error-text);
 }
 
 .sr-only {

openapi/RpgRoller.json

@@ -1,4 +1,4 @@
-{
+{
   "openapi": "3.0.1",
   "info": {
     "title": "RpgRoller API",
@@ -156,6 +156,46 @@
         }
       }
     },
+    "/api/me/theme": {
+      "put": {
+        "operationId": "updateThemePreference",
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "$ref": "#/components/schemas/UpdateThemePreferenceRequest"
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": {
+            "description": "Updated current user.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/UserSummary"
+                }
+              }
+            }
+          },
+          "400": {
+            "description": "Validation error.",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/ApiError"
+                }
+              }
+            }
+          },
+          "401": {
+            "description": "Unauthorized."
+          }
+        }
+      }
+    },
     "/api/campaigns": {
       "get": {
         "operationId": "getCampaigns",
@@ -701,12 +741,27 @@
           },
           "displayName": {
             "type": "string"
+          },
+          "roles": {
+            "type": "array",
+            "items": {
+              "type": "string"
+            }
+          },
+          "themePreference": {
+            "type": "string",
+            "nullable": true,
+            "enum": [
+              "light",
+              "dark"
+            ]
           }
         },
         "required": [
           "id",
           "username",
-          "displayName"
+          "displayName",
+          "roles"
         ]
       },
       "MeResponse": {
@@ -730,6 +785,21 @@
           "user"
         ]
       },
+      "UpdateThemePreferenceRequest": {
+        "type": "object",
+        "properties": {
+          "themePreference": {
+            "type": "string",
+            "enum": [
+              "light",
+              "dark"
+            ]
+          }
+        },
+        "required": [
+          "themePreference"
+        ]
+      },
       "RulesetDefinition": {
         "type": "object",
         "properties": {