diff --git a/app/globals.css b/app/globals.css
index 76d6f1522..a3a4d3ab3 100644
--- a/app/globals.css
+++ b/app/globals.css
@@ -187,6 +187,22 @@ body {
     "calt" 1;
 }
 
+/* Native <select> option lists are painted by the browser, not by the
+   Tailwind classes on the control, so they only honour color-scheme and an
+   explicit option colour. Themes whose --color-muted is translucent (Aurora
+   Glass dark: rgba(255,255,255,0.05)) composited to a light popup with
+   near-white text (#999). Pin options to the popover tokens, which every
+   theme defines as an opaque surface, and let dark themes ask the browser
+   for a dark popup where option colours are ignored (Safari). */
+option {
+  background-color: var(--color-popover);
+  color: var(--color-popover-foreground);
+}
+
+.dark select {
+  color-scheme: dark;
+}
+
 /* Minimalist scrollbar */
 ::-webkit-scrollbar {
   width: 8px;
diff --git a/lib/__tests__/native-select-options.test.ts b/lib/__tests__/native-select-options.test.ts
new file mode 100644
index 000000000..b3e303397
--- /dev/null
+++ b/lib/__tests__/native-select-options.test.ts
@@ -0,0 +1,77 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'fs';
+import path from 'path';
+import { BUILTIN_THEMES } from '@/lib/builtin-themes';
+
+/**
+ * The browser paints a native <select>'s option list itself; the Tailwind
+ * classes on the control (bg-muted / text-foreground) never reach it. It only
+ * honours `color-scheme` and an explicit option background/colour. Themes with
+ * a translucent --color-muted (Aurora Glass dark) therefore composited to a
+ * light popup with near-white text (#999). globals.css pins options to the
+ * popover tokens, so every theme must define those as an opaque surface.
+ *
+ * jsdom does not render native popups, so lock the stylesheet rules.
+ */
+const css = readFileSync(path.join(process.cwd(), 'app', 'globals.css'), 'utf8');
+
+/** Return the body of the first top-level `selector { ... }` rule. */
+function ruleBody(selector: string): string {
+  const idx = css.indexOf('\n' + selector + ' {');
+  expect(idx, 'no `' + selector + '` rule in globals.css').toBeGreaterThan(-1);
+  const open = css.indexOf('{', idx);
+  return css.slice(open + 1, css.indexOf('}', open));
+}
+
+/** True when a CSS colour value has no alpha channel below 1. */
+function isOpaque(value: string): boolean {
+  const v = value.trim().toLowerCase();
+  if (v === 'transparent') return false;
+  if (/^#([0-9a-f]{3}|[0-9a-f]{6})$/.test(v)) return true;
+  if (/^#[0-9a-f]{4}$/.test(v)) return v.endsWith('f');
+  if (/^#[0-9a-f]{8}$/.test(v)) return v.endsWith('ff');
+  const fn = v.match(/^(rgb|hsl)a?\((.*)\)$/);
+  if (fn) {
+    const parts = fn[2].split(/[\s,/]+/).filter(Boolean);
+    if (parts.length < 4) return true;
+    const alpha = parts[3];
+    return alpha.endsWith('%') ? parseFloat(alpha) >= 100 : parseFloat(alpha) >= 1;
+  }
+  return false;
+}
+
+/** Concrete `--color-popover` values, skipping the `@theme` alias `var(--color-popover)`. */
+function popoverValues(source: string): string[] {
+  return [...source.matchAll(/--color-popover:\s*([^;]+);/g)]
+    .map((m) => m[1].trim())
+    .filter((v) => !v.startsWith('var('));
+}
+
+describe('native <select> option colours (#999)', () => {
+  it('pins option backgrounds and text to the popover tokens', () => {
+    const body = ruleBody('option');
+    expect(body).toMatch(/background-color:\s*var\(--color-popover\)/);
+    expect(body).toMatch(/(?:^|[^-])color:\s*var\(--color-popover-foreground\)/);
+  });
+
+  it('asks the browser for a dark popup in dark mode', () => {
+    expect(ruleBody('.dark select')).toMatch(/color-scheme:\s*dark/);
+  });
+
+  it('keeps the base light and dark popover surfaces opaque', () => {
+    const values = popoverValues(css);
+    expect(values.length).toBeGreaterThanOrEqual(2);
+    for (const v of values) expect(isOpaque(v), `globals.css --color-popover: ${v}`).toBe(true);
+  });
+
+  it.each(BUILTIN_THEMES.map((t) => [t.name, t] as const))(
+    '%s defines an opaque popover in every variant',
+    (_name, theme) => {
+      const values = popoverValues(theme.css);
+      expect(values.length, 'theme css should set --color-popover').toBeGreaterThanOrEqual(
+        theme.variants.length
+      );
+      for (const v of values) expect(isOpaque(v), `--color-popover: ${v}`).toBe(true);
+    }
+  );
+});