:root {
  color-scheme: light;
  --color-bg: #fafbfc;
  --color-surface: #ffffff;
  --color-surface-alt: #f1f4f8;
  --color-text: #18212e;
  --color-muted: #566375;
  --color-line: #dce2e9;
  --color-accent: #245bc4;
  --color-accent-soft: #eaf0fc;
  --color-on-accent: #ffffff;
  --color-focus: #245bc4;
  --shadow-panel: 0 14px 40px #162c4910;
  --font-sans: "Segoe UI", -apple-system, BlinkMacSystemFont, Arial, sans-serif;
  --font-mono: "Cascadia Code", Consolas, "Liberation Mono", monospace;
  --content-width: 1280px;
  --reading-width: 65ch;
  --gutter: clamp(1.25rem, 4vw, 4rem);
  --radius: 10px;
}
:root[data-theme="dark"] {
  color-scheme: dark;
  --color-bg: #101318;
  --color-surface: #171c23;
  --color-surface-alt: #1d242e;
  --color-text: #edf1f7;
  --color-muted: #a5b0c0;
  --color-line: #303946;
  --color-accent: #8eb6ff;
  --color-accent-soft: #202e46;
  --color-on-accent: #10203e;
  --color-focus: #8eb6ff;
  --shadow-panel: 0 14px 40px #00000026;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --color-bg: #101318;
    --color-surface: #171c23;
    --color-surface-alt: #1d242e;
    --color-text: #edf1f7;
    --color-muted: #a5b0c0;
    --color-line: #303946;
    --color-accent: #8eb6ff;
    --color-accent-soft: #202e46;
    --color-on-accent: #10203e;
    --color-focus: #8eb6ff;
    --shadow-panel: 0 14px 40px #00000026;
  }
}


/* System-only CJK fallbacks. Noto is used only if installed; no webfont downloads. */
:lang(ja) { --font-sans: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Yu Gothic UI', 'Yu Gothic', Meiryo, 'Hiragino Sans', 'Hiragino Kaku Gothic ProN', 'Noto Sans CJK JP', sans-serif; }
:lang(zh-Hans) { --font-sans: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Microsoft YaHei UI', 'Microsoft YaHei', 'PingFang SC', 'Noto Sans CJK SC', sans-serif; }
:lang(zh-Hant) { --font-sans: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Microsoft JhengHei UI', 'Microsoft JhengHei', 'PingFang TC', sans-serif; }
:lang(ko) { --font-sans: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Malgun Gothic', 'Apple SD Gothic Neo', 'Noto Sans KR', sans-serif; word-break: keep-all; }