fix(ui): stop body data-theme from shadowing theme preset tokens

applyTheme() mirrors the active mode onto <body> as data-theme="dark", but the theme preset is only ever written to <html>. The palette token blocks in tokens/colors.css and base.css used the bare attribute selector [data-theme="dark"], so <body> matched them on its own and re-declared the default dark palette (#1a1a1a / #2d2d2d / ...) directly on the body, where it shadowed the preset values inherited from <html>. Every non-default preset therefore painted the selected accent over the default preset's background, surface, text and border tokens, and flipped into that state ~200ms after load, when initTheme() first touched <body> — the accent-tinted background flash seen on reload and nav-tab switches. Reached only in dark mode, since light mode has no [data-theme="light"] token block. Scope the palette token blocks to :root so a data-theme attribute on any descendant (only <body> has one) can no longer re-declare them; descendant rules such as [data-theme="dark"] .foo still match through <html>. Add a regression guard that fails on bare attribute token blocks.
2026-09-28 14:34:09 -03:00 · 2026-09-27 21:48:58 +08:00
4 changed files with 81 additions and 13 deletions
@@ -81,7 +81,7 @@ body {
    --badge-skip-refresh-glow: var(--color-skip-refresh-glow);
 }

-[data-theme="dark"] {
+:root[data-theme="dark"] {
    --bg-color: var(--bg-base);
    --text-color: var(--text-primary);
    --text-muted: var(--text-secondary);
@@ -572,7 +572,7 @@
 }

 /* Dark mode: use each preset's dark-mode accent lightness for visibility.
-   These match the --color-accent-l values from [data-theme="dark"][data-theme-preset="..."]
+   These match the --color-accent-l values from :root[data-theme="dark"][data-theme-preset="..."]
   in tokens/colors.css so the swatch accurately previews what the theme looks like. */

 [data-theme="dark"] .preset-swatch-default {
@@ -78,7 +78,7 @@
  --favorite-glow: oklch(65% 0.15 85 / 0.5);
 }

-[data-theme="dark"] {
+:root[data-theme="dark"] {
  --bg-base: #1a1a1a;
  --bg-elevated: oklch(25% 0.02 256 / 0.98);
  --bg-overlay: oklch(0% 0 0 / 0.75);
@@ -118,7 +118,7 @@

 /* ── Preset: Nord ──────────────────────────────────────────── */

-[data-theme-preset="nord"] {
+:root[data-theme-preset="nord"] {
  --color-accent-h: 213;
  --color-accent-c: 0.18;
  --color-accent-l: 62%;
@@ -152,7 +152,7 @@
  --favorite-glow: oklch(72% 0.14 85 / 0.5);
 }

-[data-theme="dark"][data-theme-preset="nord"] {
+:root[data-theme="dark"][data-theme-preset="nord"] {
  --color-accent-h: 213;
  --color-accent-c: 0.18;
  --color-accent-l: 68%;
@@ -188,7 +188,7 @@

 /* ── Preset: Midnight ───────────────────────────────────────── */

-[data-theme-preset="midnight"] {
+:root[data-theme-preset="midnight"] {
  --color-accent-h: 300;
  --color-accent-c: 0.15;
  --color-accent-l: 52%;
@@ -222,7 +222,7 @@
  --favorite-glow: oklch(72% 0.16 85 / 0.5);
 }

-[data-theme="dark"][data-theme-preset="midnight"] {
+:root[data-theme="dark"][data-theme-preset="midnight"] {
  --color-accent-h: 300;
  --color-accent-c: 0.14;
  --color-accent-l: 68%;
@@ -258,7 +258,7 @@

 /* ── Preset: Monokai ───────────────────────────────────────── */

-[data-theme-preset="monokai"] {
+:root[data-theme-preset="monokai"] {
  --color-accent-h: 190;
  --color-accent-c: 0.24;
  --color-accent-l: 72%;
@@ -291,7 +291,7 @@
  --favorite-glow: oklch(72% 0.16 85 / 0.5);
 }

-[data-theme="dark"][data-theme-preset="monokai"] {
+:root[data-theme="dark"][data-theme-preset="monokai"] {
  --color-accent-h: 190;
  --color-accent-c: 0.24;
  --color-accent-l: 72%;
@@ -326,7 +326,7 @@

 /* ── Preset: Dracula ───────────────────────────────────────── */

-[data-theme-preset="dracula"] {
+:root[data-theme-preset="dracula"] {
  --color-accent-h: 265;
  --color-accent-c: 0.24;
  --color-accent-l: 68%;
@@ -359,7 +359,7 @@
  --favorite-glow: oklch(72% 0.16 85 / 0.5);
 }

-[data-theme="dark"][data-theme-preset="dracula"] {
+:root[data-theme="dark"][data-theme-preset="dracula"] {
  --color-accent-h: 265;
  --color-accent-c: 0.24;
  --color-accent-l: 72%;
@@ -394,7 +394,7 @@

 /* ── Preset: Solarized ─────────────────────────────────────── */

-[data-theme-preset="solarized"] {
+:root[data-theme-preset="solarized"] {
  --color-accent-h: 175;
  --color-accent-c: 0.18;
  --color-accent-l: 55%;
@@ -429,7 +429,7 @@
  --favorite-glow: oklch(68% 0.16 75 / 0.5);
 }

-[data-theme="dark"][data-theme-preset="solarized"] {
+:root[data-theme="dark"][data-theme-preset="solarized"] {
  --color-accent-h: 175;
  --color-accent-c: 0.18;
  --color-accent-l: 60%;
@@ -0,0 +1,68 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'fs';
+import path from 'path';
+
+// Regression guard: theme palette tokens may only be declared on the root element.
+//
+// `applyTheme()` (static/js/utils/uiHelpers.js, and Header.setThemeMode) mirrors
+// the active mode onto <body> as `data-theme="dark"`, but the theme *preset* is
+// only ever written to <html> (`data-theme-preset`). While the token blocks in
+// tokens/colors.css used the bare attribute selector `[data-theme="dark"]`, the
+// body matched that block on its own and re-declared the DEFAULT dark palette
+// (#1a1a1a / #2d2d2d), shadowing the preset palette it inherited from <html>.
+// The page painted the selected preset's accent but the default preset's
+// backgrounds/surfaces/text, and flipped into that state ~200ms after load when
+// initTheme() first touched <body> — the accent-tinted background flash on
+// reload and nav-tab switches, visible under every preset except "default".
+// Root-scoping the token blocks keeps <body>'s data-theme inert.
+describe('Theme token scope', () => {
+  const repoRoot = path.resolve(__dirname, '../../..');
+  const read = (rel) => readFileSync(path.join(repoRoot, rel), 'utf-8');
+  const stripComments = (css) => css.replace(/\/\*[\s\S]*?\*\//g, '');
+
+  const COLOR_TOKENS = read('static/css/tokens/colors.css');
+  const BASE_CSS = read('static/css/base.css');
+
+  // Selectors that declare a palette token, e.g. `--bg-base:` / `--lora-surface:`.
+  const tokenDeclaringSelectors = (css) => {
+    const selectors = [];
+    const ruleRe = /([^{}]+)\{([^{}]*)\}/g;
+    let match;
+    while ((match = ruleRe.exec(stripComments(css)))) {
+      const selector = match[1].trim();
+      const declaresPaletteToken = /(^|[;\s])--(?:bg|surface|text|border|color|favorite|lora|badge|card)-[\w-]+\s*:/.test(
+        match[2]
+      );
+      if (declaresPaletteToken) selectors.push(selector);
+    }
+    return selectors;
+  };
+
+  const isRootScoped = (selector) =>
+    selector.split(',').every((part) => /^\s*(:root|html)\b/.test(part));
+
+  it('declares every colors.css palette token on :root', () => {
+    const selectors = tokenDeclaringSelectors(COLOR_TOKENS);
+    expect(selectors.length).toBeGreaterThan(0);
+    expect(selectors.filter((selector) => !isRootScoped(selector))).toEqual([]);
+  });
+
+  it('declares every base.css palette alias on :root', () => {
+    const selectors = tokenDeclaringSelectors(BASE_CSS);
+    expect(selectors.length).toBeGreaterThan(0);
+    expect(selectors.filter((selector) => !isRootScoped(selector))).toEqual([]);
+  });
+
+  it('keeps dark/preset token blocks anchored to the root element', () => {
+    const css = stripComments(COLOR_TOKENS);
+    expect(css).toContain(':root[data-theme="dark"] {');
+    for (const preset of ['nord', 'midnight', 'monokai', 'dracula', 'solarized']) {
+      expect(css).toContain(`:root[data-theme-preset="${preset}"] {`);
+      expect(css).toContain(`:root[data-theme="dark"][data-theme-preset="${preset}"] {`);
+    }
+    // No bare attribute selector may open a rule: <body> carries data-theme
+    // without the preset, so such a block would re-declare the default palette.
+    expect(css).not.toMatch(/(^|\n)\s*\[data-theme/);
+    expect(stripComments(BASE_CSS)).not.toMatch(/(^|\n)\s*\[data-theme/);
+  });
+});