Add dark and light theme with OS preference support

Follow OS color scheme by default, with a three-way toggle
(System / Light / Dark) in the kebab menu. Light theme uses warm,
neutral tones with soft card-to-background contrast. Semantic colors
(damage, healing, conditions) keep their hue across themes.

Closes #10

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/components/__tests__/combatant-row.test.tsx

@@ -75,7 +75,7 @@ describe("CombatantRow", () => {
 	it("active combatant gets active border styling", () => {
 		const { container } = renderRow({ isActive: true });
 		const row = container.firstElementChild;
-		expect(row?.className).toContain("border-accent/40");
+		expect(row?.className).toContain("border-active-row-border");
 	});
 
 	it("unconscious combatant (currentHp === 0) gets dimmed styling", () => {

apps/web/src/components/action-bar.tsx

@@ -6,7 +6,10 @@ import {
 	Import,
 	Library,
 	Minus,
+	Monitor,
+	Moon,
 	Plus,
+	Sun,
 	Users,
 } from "lucide-react";
 import React, { type RefObject, useDeferredValue, useState } from "react";
@@ -43,6 +46,8 @@ interface ActionBarProps {
 	rollAllInitiativeDisabled?: boolean;
 	onOpenSourceManager?: () => void;
 	autoFocus?: boolean;
+	themePreference?: "system" | "light" | "dark";
+	onCycleTheme?: () => void;
 }
 
 function creatureKey(r: SearchResult): string {
@@ -171,7 +176,7 @@ function AddModeSuggestions({
 													>
 														<Minus className="h-3 w-3" />
 													</button>
-													<span className="min-w-5 rounded-full bg-accent px-1.5 py-0.5 text-center font-medium text-foreground">
+													<span className="min-w-5 rounded-full bg-accent px-1.5 py-0.5 text-center font-medium text-primary-foreground">
 														{queued.count}
 													</span>
 													<button
@@ -215,12 +220,26 @@ function AddModeSuggestions({
 	);
 }
 
+const THEME_ICONS = {
+	system: Monitor,
+	light: Sun,
+	dark: Moon,
+} as const;
+
+const THEME_LABELS = {
+	system: "Theme: System",
+	light: "Theme: Light",
+	dark: "Theme: Dark",
+} as const;
+
 function buildOverflowItems(opts: {
 	onManagePlayers?: () => void;
 	onOpenSourceManager?: () => void;
 	bestiaryLoaded: boolean;
 	onBulkImport?: () => void;
 	bulkImportDisabled?: boolean;
+	themePreference?: "system" | "light" | "dark";
+	onCycleTheme?: () => void;
 }): OverflowMenuItem[] {
 	const items: OverflowMenuItem[] = [];
 	if (opts.onManagePlayers) {
@@ -245,6 +264,16 @@ function buildOverflowItems(opts: {
 			disabled: opts.bulkImportDisabled,
 		});
 	}
+	if (opts.onCycleTheme) {
+		const pref = opts.themePreference ?? "system";
+		const ThemeIcon = THEME_ICONS[pref];
+		items.push({
+			icon: <ThemeIcon className="h-4 w-4" />,
+			label: THEME_LABELS[pref],
+			onClick: opts.onCycleTheme,
+			keepOpen: true,
+		});
+	}
 	return items;
 }
 
@@ -265,6 +294,8 @@ export function ActionBar({
 	rollAllInitiativeDisabled,
 	onOpenSourceManager,
 	autoFocus,
+	themePreference,
+	onCycleTheme,
 }: Readonly<ActionBarProps>) {
 	const [nameInput, setNameInput] = useState("");
 	const [suggestions, setSuggestions] = useState<SearchResult[]>([]);
@@ -454,6 +485,8 @@ export function ActionBar({
 		bestiaryLoaded,
 		onBulkImport,
 		bulkImportDisabled,
+		themePreference,
+		onCycleTheme,
 	});
 
 	return (

apps/web/src/components/combatant-row.tsx

@@ -367,9 +367,9 @@ function rowBorderClass(
 	isConcentrating: boolean | undefined,
 ): string {
 	if (isActive && isConcentrating)
-		return "border border-l-2 border-accent/40 border-l-purple-400 bg-accent/10 card-glow";
+		return "border border-l-2 border-active-row-border border-l-purple-400 bg-active-row-bg card-glow";
 	if (isActive)
-		return "border border-l-2 border-accent/40 bg-accent/10 card-glow";
+		return "border border-l-2 border-active-row-border bg-active-row-bg card-glow";
 	if (isConcentrating)
 		return "border border-l-2 border-transparent border-l-purple-400";
 	return "border border-l-2 border-transparent";

apps/web/src/components/hp-adjust-popover.tsx

@@ -113,7 +113,7 @@ export function HpAdjustPopover({ onAdjust, onClose }: HpAdjustPopoverProps) {
 				<button
 					type="button"
 					disabled={!isValid}
-					className="inline-flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-red-400 transition-colors hover:bg-red-950 hover:text-red-300 disabled:pointer-events-none disabled:opacity-50"
+					className="inline-flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-red-400 transition-colors hover:bg-hp-damage-hover-bg hover:text-red-300 disabled:pointer-events-none disabled:opacity-50"
 					onClick={() => applyDelta(-1)}
 					title="Apply damage"
 					aria-label="Apply damage"
@@ -123,7 +123,7 @@ export function HpAdjustPopover({ onAdjust, onClose }: HpAdjustPopoverProps) {
 				<button
 					type="button"
 					disabled={!isValid}
-					className="inline-flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-emerald-400 transition-colors hover:bg-emerald-950 hover:text-emerald-300 disabled:pointer-events-none disabled:opacity-50"
+					className="inline-flex h-7 w-7 shrink-0 items-center justify-center rounded-md text-emerald-400 transition-colors hover:bg-hp-heal-hover-bg hover:text-emerald-300 disabled:pointer-events-none disabled:opacity-50"
 					onClick={() => applyDelta(1)}
 					title="Apply healing"
 					aria-label="Apply healing"

apps/web/src/components/stat-block.tsx

@@ -30,7 +30,7 @@ function PropertyLine({
 
 function SectionDivider() {
 	return (
-		<div className="my-2 h-px bg-gradient-to-r from-amber-800/60 via-amber-700/40 to-transparent" />
+		<div className="my-2 h-px bg-gradient-to-r from-stat-divider-from via-stat-divider-via to-transparent" />
 	);
 }
 
@@ -54,7 +54,7 @@ export function StatBlock({ creature }: Readonly<StatBlockProps>) {
 		<div className="space-y-1 text-foreground">
 			{/* Header */}
 			<div>
-				<h2 className="font-bold text-amber-400 text-xl">{creature.name}</h2>
+				<h2 className="font-bold text-stat-heading text-xl">{creature.name}</h2>
 				<p className="text-muted-foreground text-sm italic">
 					{creature.size} {creature.type}, {creature.alignment}
 				</p>
@@ -194,7 +194,7 @@ export function StatBlock({ creature }: Readonly<StatBlockProps>) {
 			{creature.actions && creature.actions.length > 0 && (
 				<>
 					<SectionDivider />
-					<h3 className="font-bold text-amber-400 text-base">Actions</h3>
+					<h3 className="font-bold text-base text-stat-heading">Actions</h3>
 					<div className="space-y-2">
 						{creature.actions.map((a) => (
 							<div key={a.name} className="text-sm">
@@ -209,7 +209,9 @@ export function StatBlock({ creature }: Readonly<StatBlockProps>) {
 			{creature.bonusActions && creature.bonusActions.length > 0 && (
 				<>
 					<SectionDivider />
-					<h3 className="font-bold text-amber-400 text-base">Bonus Actions</h3>
+					<h3 className="font-bold text-base text-stat-heading">
+						Bonus Actions
+					</h3>
 					<div className="space-y-2">
 						{creature.bonusActions.map((a) => (
 							<div key={a.name} className="text-sm">
@@ -224,7 +226,7 @@ export function StatBlock({ creature }: Readonly<StatBlockProps>) {
 			{creature.reactions && creature.reactions.length > 0 && (
 				<>
 					<SectionDivider />
-					<h3 className="font-bold text-amber-400 text-base">Reactions</h3>
+					<h3 className="font-bold text-base text-stat-heading">Reactions</h3>
 					<div className="space-y-2">
 						{creature.reactions.map((a) => (
 							<div key={a.name} className="text-sm">
@@ -239,7 +241,7 @@ export function StatBlock({ creature }: Readonly<StatBlockProps>) {
 			{!!creature.legendaryActions && (
 				<>
 					<SectionDivider />
-					<h3 className="font-bold text-amber-400 text-base">
+					<h3 className="font-bold text-base text-stat-heading">
 						Legendary Actions
 					</h3>
 					<p className="text-muted-foreground text-sm italic">

apps/web/src/components/ui/overflow-menu.tsx

@@ -7,6 +7,7 @@ export interface OverflowMenuItem {
 	readonly label: string;
 	readonly onClick: () => void;
 	readonly disabled?: boolean;
+	readonly keepOpen?: boolean;
 }
 
 interface OverflowMenuProps {
@@ -58,7 +59,7 @@ export function OverflowMenu({ items }: OverflowMenuProps) {
 							disabled={item.disabled}
 							onClick={() => {
 								item.onClick();
-								setOpen(false);
+								if (!item.keepOpen) setOpen(false);
 							}}
 						>
 							{item.icon}