:root {
  --header-height: 68px;
  --page: #f7f5f0;
  --surface: #fffdf9;
  --surface-alt: #f0ece5;
  --ink: #2b2926;
  --muted: #6e6961;
  --line: #e3ddd3;
  --primary: #c75b3e;
  --primary-strong: #a94730;
  --primary-soft: #f5e2da;
  --quote: #fbefe9;
  --code: #262421;
  --code-ink: #f5eee6;
  --shadow: 0 18px 45px rgb(60 45 35 / 8%);
  --ease: cubic-bezier(.22, .61, .36, 1);
  color-scheme: light;
}

[data-theme="dark"] {
  --page: #211f1d;
  --surface: #292725;
  --surface-alt: #332f2b;
  --ink: #f4eee6;
  --muted: #b9afa4;
  --line: #49423b;
  --primary: #e39479;
  --primary-strong: #f2b19a;
  --primary-soft: #4a3029;
  --quote: #3a2c27;
  --code: #171615;
  --code-ink: #f7eee5;
  --shadow: 0 18px 45px rgb(0 0 0 / 22%);
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--page);
  background-image: radial-gradient(circle at 12% 0%, rgb(199 91 62 / 5%), transparent 34rem);
  color: var(--ink);
  font: 16px/1.82 -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  text-rendering: optimizeLegibility;
}
a { color: var(--primary-strong); text-underline-offset: 4px; transition: color 180ms var(--ease); }
a:hover { color: var(--primary); }
button { font: inherit; touch-action: manipulation; }
:focus-visible { outline: 3px solid var(--primary); outline-offset: 3px; }
.skip-link { position: fixed; z-index: 100; top: 10px; left: 10px; padding: 8px 12px; border-radius: 6px; background: var(--ink); color: var(--page); transform: translateY(-150%); transition: transform 180ms var(--ease); }
.skip-link:focus { transform: translateY(0); }
.reading-progress { position: fixed; z-index: 60; inset: 0 0 auto; height: 3px; background: transparent; }
.reading-progress span { display: block; width: 0; height: 100%; background: var(--primary); transition: width 100ms linear; }

.site-header {
  position: sticky;
  z-index: 50;
  top: 0;
  display: flex;
  height: var(--header-height);
  align-items: center;
  justify-content: space-between;
  padding: 0 32px;
  border-bottom: 1px solid rgb(227 221 211 / 80%);
  background: color-mix(in srgb, var(--page) 92%, transparent);
  backdrop-filter: blur(16px);
}
.brand { display: inline-flex; min-height: 44px; align-items: center; gap: 10px; color: var(--ink); font-weight: 700; letter-spacing: -.02em; text-decoration: none; }
.brand svg { width: 26px; height: 26px; fill: none; stroke: var(--primary); stroke-linecap: round; stroke-linejoin: round; stroke-width: 1.7; }
.brand small { margin-left: 3px; color: var(--muted); font-size: 11px; font-weight: 500; letter-spacing: .08em; }
.header-actions { display: flex; align-items: center; gap: 8px; }
.header-link { padding: 8px 10px; font-size: 13px; font-weight: 600; }
.icon-button { display: grid; width: 44px; height: 44px; place-items: center; padding: 0; border: 1px solid transparent; border-radius: 12px; background: transparent; color: var(--muted); cursor: pointer; transition: background 180ms var(--ease), color 180ms var(--ease), transform 180ms var(--ease); }
.icon-button:hover { background: var(--primary-soft); color: var(--primary-strong); }
.icon-button:active { transform: scale(.95); }
.icon-button svg { width: 19px; height: 19px; fill: none; stroke: currentColor; stroke-linecap: round; stroke-width: 1.6; }
.menu-button { display: none; }

.page-shell { display: grid; grid-template-columns: 220px minmax(0, 760px); gap: 92px; width: min(1072px, calc(100% - 56px)); margin: 0 auto; }
.sidebar { position: sticky; top: calc(var(--header-height) + 24px); align-self: start; max-height: calc(100vh - var(--header-height) - 48px); padding: 42px 0; overflow: auto; }
.nav-label { margin: 0 0 14px; color: var(--muted); font-size: 10px; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; }
.tutorial-nav { display: grid; gap: 2px; }
.tutorial-nav a { display: grid; grid-template-columns: 25px 1fr; gap: 6px; min-height: 36px; align-items: center; padding: 6px 8px; border-left: 2px solid transparent; color: var(--muted); font-size: 12px; line-height: 1.45; text-decoration: none; transition: border-color 180ms var(--ease), background 180ms var(--ease), color 180ms var(--ease), transform 180ms var(--ease); }
.tutorial-nav a span { color: color-mix(in srgb, var(--muted) 62%, transparent); font: 10px ui-monospace, SFMono-Regular, Consolas, monospace; }
.tutorial-nav a:hover, .tutorial-nav a.active { border-color: var(--primary); background: var(--primary-soft); color: var(--primary-strong); transform: translateX(3px); }
.tutorial-nav a.nav-level-1 { font-weight: 700; }
.tutorial-nav a.nav-level-2 { padding-left: 14px; font-size: 11px; }
.nav-loading { color: var(--muted); font-size: 12px; }
.sidebar-note { max-width: 190px; margin-top: 36px; padding-top: 16px; border-top: 1px solid var(--line); font-size: 12px; }
.sidebar-note strong { color: var(--primary-strong); font-size: 11px; letter-spacing: .06em; text-transform: uppercase; }
.sidebar-note p { margin: 7px 0 0; color: var(--muted); line-height: 1.65; }
.sidebar-note code { padding: 1px 4px; background: var(--surface-alt); color: var(--primary-strong); font-size: 11px; }

main { min-width: 0; }
.markdown-content { min-height: 75vh; padding: 82px 0 16px; }
.article-header { margin-bottom: 48px; }
.article-kicker { margin: 0 0 12px !important; color: var(--primary-strong) !important; font-size: 11px !important; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; }
.article-header h1 { margin-bottom: 14px !important; font: 400 clamp(40px, 5vw, 58px)/1.16 Georgia, "Times New Roman", serif; letter-spacing: -.04em; }
.article-byline { margin: 0 !important; color: var(--muted); font-size: 13px !important; }
.markdown-content > h1 { max-width: 760px; margin: 0 0 30px; font: 400 clamp(40px, 5vw, 62px)/1.12 Georgia, "Times New Roman", serif; letter-spacing: -.045em; }
.markdown-content > h1 + p { color: var(--muted); font-size: 18px; }
.markdown-content h2 { position: relative; margin: 78px 0 19px; padding-top: 30px; border-top: 1px solid var(--line); font: 400 clamp(28px, 3vw, 36px)/1.25 Georgia, "Times New Roman", serif; letter-spacing: -.025em; scroll-margin-top: 92px; }
.markdown-content h2::before { position: absolute; top: -1px; left: 0; width: 46px; height: 2px; background: var(--primary); content: ""; }
.markdown-content h3 { margin: 38px 0 10px; font-size: 20px; line-height: 1.4; letter-spacing: -.015em; scroll-margin-top: 92px; }
.markdown-content p { max-width: 72ch; margin: 16px 0; color: var(--muted); }
.markdown-content h1, .markdown-content h2, .markdown-content h3, .markdown-content h4 { color: var(--ink); }
.markdown-content h2 + p, .markdown-content h3 + p { margin-top: 8px; }
.markdown-content strong { color: var(--ink); font-weight: 700; }
.markdown-content code { padding: 2px 6px; border: 1px solid var(--line); border-radius: 5px; background: var(--surface-alt); color: var(--primary-strong); font: .86em/1.45 ui-monospace, SFMono-Regular, Consolas, monospace; }
.markdown-content pre { margin: 0; overflow: auto; }
.markdown-content pre code { display: block; padding: 19px 20px; border: 0; border-radius: 0 0 12px 12px; background: transparent; color: var(--code-ink); font-size: 13px; line-height: 1.72; white-space: pre; }
.code-block { margin: 24px 0; overflow: hidden; border: 1px solid var(--line); border-radius: 12px; background: var(--code); box-shadow: var(--shadow); }
.code-header { display: flex; min-height: 42px; align-items: center; justify-content: space-between; padding: 7px 10px 7px 16px; border-bottom: 1px solid rgb(255 255 255 / 12%); color: #b9afa4; font: 11px ui-monospace, SFMono-Regular, Consolas, monospace; }
.code-header button { min-width: 44px; min-height: 32px; padding: 4px 9px; border: 1px solid rgb(255 255 255 / 22%); border-radius: 6px; background: transparent; color: #d8cfc4; font-size: 11px; cursor: pointer; transition: background 180ms var(--ease), color 180ms var(--ease), transform 180ms var(--ease); }
.code-header button:hover { background: rgb(255 255 255 / 10%); color: white; }
.code-header button:active { transform: scale(.96); }
.markdown-content img { display: block; max-width: 100%; height: auto; margin: 30px auto; border: 1px solid var(--line); border-radius: 14px; box-shadow: 0 16px 38px rgb(60 45 35 / 10%); }
.markdown-content figure { margin: 30px 0; }
.markdown-content figure img { margin: 0 auto; }
.markdown-content figcaption { margin-top: 8px; color: var(--muted); font-size: 12px; text-align: center; }
.markdown-content blockquote { margin: 26px 0; padding: 5px 22px; border-left: 3px solid var(--primary); border-radius: 0 10px 10px 0; background: var(--quote); }
.markdown-content blockquote p { margin: 10px 0; color: var(--ink); }
.markdown-content ul, .markdown-content ol { max-width: 72ch; margin: 14px 0 24px; padding-left: 28px; color: var(--muted); }
.markdown-content li { padding-left: 5px; }
.markdown-content li + li { margin-top: 7px; }
.markdown-content hr { margin: 48px 0; border: 0; border-top: 1px solid var(--line); }
.loading-state, .error-state { padding: 30px; border: 1px solid var(--line); border-radius: 12px; background: var(--surface); color: var(--muted); }
.loading-state { animation: breathe 1.4s ease-in-out infinite; }
.error-state h1 { margin-top: 0; color: var(--ink); font-family: Georgia, "Times New Roman", serif; font-weight: 400; }
.error-state a { font-weight: 700; }
footer { display: flex; align-items: center; justify-content: space-between; gap: 24px; margin-top: 58px; padding: 28px 0 42px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }
footer p { margin: 0; }
footer div { display: flex; flex-wrap: wrap; gap: 18px; }
.toast { position: fixed; z-index: 100; right: 22px; bottom: 22px; padding: 12px 16px; border: 1px solid var(--line); border-radius: 9px; background: var(--ink); box-shadow: var(--shadow); color: var(--page); font-size: 13px; font-weight: 700; opacity: 0; pointer-events: none; transform: translateY(12px); transition: opacity 180ms var(--ease), transform 180ms var(--ease); }
.toast.show { opacity: 1; transform: translateY(0); }

@keyframes fade-up { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: translateY(0); } }
@keyframes breathe { 0%, 100% { opacity: .55; } 50% { opacity: 1; } }
.is-loaded .article-header { animation: fade-up 280ms var(--ease) both; }
.is-loaded .markdown-content > figure:first-of-type { animation: fade-up 320ms 70ms var(--ease) both; }

@media (max-width: 1020px) {
  .menu-button { display: grid; }
  .page-shell { grid-template-columns: 1fr; width: min(760px, calc(100% - 44px)); }
  .sidebar { position: fixed; z-index: 45; top: var(--header-height); left: 0; width: min(84vw, 310px); height: calc(100dvh - var(--header-height)); max-height: none; padding: 30px 22px; border-right: 1px solid var(--line); background: var(--page); box-shadow: 16px 0 40px rgb(40 30 24 / 18%); transform: translateX(-105%); transition: transform 240ms var(--ease); }
  .sidebar.open { transform: translateX(0); }
  body:has(.sidebar.open)::before { position: fixed; z-index: 40; inset: var(--header-height) 0 0; background: rgb(43 41 38 / 42%); content: ""; }
}
@media (max-width: 720px) {
  .site-header { padding: 0 14px; }
  .brand small, .header-link { display: none; }
  .page-shell { width: min(100% - 32px, 680px); }
  .markdown-content { padding-top: 52px; }
  .article-header { margin-bottom: 38px; }
  .markdown-content > h1 { font-size: clamp(37px, 12vw, 56px); }
  .markdown-content > h1 + p { font-size: 16px; }
  .markdown-content h2 { margin-top: 58px; }
  .markdown-content pre code { font-size: 12px; }
  footer { align-items: flex-start; flex-direction: column; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}
@media print {
  .site-header, .sidebar, .reading-progress, .code-header button, .toast { display: none !important; }
  .page-shell { display: block; width: 100%; }
  .markdown-content { padding-top: 0; }
  body { background: white; color: black; }
  .markdown-content h2 { break-before: auto; }
}