/* vibe-backend site — minimal, monochrome + one accent. */
:root {
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", Inter, "Segoe UI", "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", system-ui, sans-serif;
  --mono: "SF Mono", ui-monospace, Menlo, Consolas, "DejaVu Sans Mono", "Liberation Mono", "Noto Sans Mono CJK TC", monospace;
  --bg: #fff; --bg2: #f5f5f7; --fg: #1d1d1f; --mut: #6e6e73; --line: #d2d2d7;
  --card: #fff; --code-bg: #f5f5f7; --accent: #0071e3; --accent-fg: #fff; --header: rgba(255,255,255,.72);
  --k: #ad3da4; --s: #c41a16; --n: #1c00cf; --c: #707f8c; --t: #3f6e74; --f: #4b21b0;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #000; --bg2: #0d0d0f; --fg: #f5f5f7; --mut: #a1a1a6; --line: #2c2c2e;
    --card: #151517; --code-bg: #111113; --accent: #2997ff; --header: rgba(0,0,0,.72);
    --k: #ff7ab2; --s: #ff8170; --n: #d9c97c; --c: #7f8c98; --t: #6bdfff; --f: #b281eb;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #000; --bg2: #0d0d0f; --fg: #f5f5f7; --mut: #a1a1a6; --line: #2c2c2e;
  --card: #151517; --code-bg: #111113; --accent: #2997ff; --header: rgba(0,0,0,.72);
  --k: #ff7ab2; --s: #ff8170; --n: #d9c97c; --c: #7f8c98; --t: #6bdfff; --f: #b281eb;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 72px; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 17px/1.6 var(--font); letter-spacing: -.01em; -webkit-font-smoothing: antialiased; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code { font-family: var(--mono); font-size: .86em; background: var(--bg2); padding: .12em .4em; border-radius: 6px; overflow-wrap: anywhere; }
pre { background: var(--code-bg); border-radius: 14px; padding: 1.1em 1.25em; overflow: auto; font-size: 14px; line-height: 1.6; }
pre code { background: none; padding: 0; font-size: inherit; overflow-wrap: normal; }
h1, h2, h3 { letter-spacing: -.025em; line-height: 1.1; font-weight: 700; }

/* header */
.top { position: sticky; top: 0; z-index: 10; background: var(--header); backdrop-filter: saturate(180%) blur(20px); -webkit-backdrop-filter: saturate(180%) blur(20px); border-bottom: 1px solid var(--line); }
.bar { max-width: 1120px; margin: 0 auto; height: 52px; padding: 0 22px; display: flex; align-items: center; gap: 28px; }
.brand { font-weight: 700; font-size: 18px; color: var(--fg); letter-spacing: -.02em; }
.brand span { color: var(--mut); font-weight: 500; }
.brand:hover { text-decoration: none; }
#nav { display: flex; gap: 26px; flex: 1; font-size: 13px; }
#nav a { color: var(--fg); opacity: .8; }
#nav a:hover, #nav a[aria-current] { opacity: 1; text-decoration: none; }
#nav a[aria-current] { font-weight: 600; }
.tools { display: flex; align-items: center; gap: 10px; }
.lang { display: flex; border: 1px solid var(--line); border-radius: 999px; padding: 2px; font-size: 12px; }
.lang a, .lang .cur { padding: 2px 10px; border-radius: 999px; color: var(--mut); }
.lang .cur { background: var(--fg); color: var(--bg); font-weight: 600; }
.lang a:hover { color: var(--fg); text-decoration: none; }
.theme { background: none; border: 0; color: var(--fg); cursor: pointer; padding: 6px; border-radius: 50%; display: grid; opacity: .8; }
.theme:hover { opacity: 1; background: var(--bg2); }
.menu { display: none; background: none; border: 0; width: 36px; height: 36px; padding: 8px; cursor: pointer; flex-direction: column; justify-content: center; gap: 6px; }
.menu span { display: block; height: 1.5px; background: var(--fg); border-radius: 2px; transition: transform .25s; }
.nav-open .menu span:first-child { transform: translateY(3.75px) rotate(45deg); }
.nav-open .menu span:last-child { transform: translateY(-3.75px) rotate(-45deg); }

/* layout */
.page { max-width: 980px; margin: 0 auto; padding: 72px 22px 96px; }
.page.wide { max-width: none; padding: 0; }
.page.wide > main > section { padding: 120px 22px; }
.page.wide > main > section > * { max-width: 1080px; margin-left: auto; margin-right: auto; }
.eyebrow { color: var(--accent); font-weight: 600; font-size: 17px; margin: 0 0 .6em; letter-spacing: 0; }
.lead { font-size: 21px; line-height: 1.45; color: var(--mut); max-width: 720px; }
.sub { color: var(--mut); font-size: 19px; }
.center { text-align: center; }
.btn { display: inline-block; background: var(--accent); color: var(--accent-fg); padding: 12px 24px; border-radius: 999px; font-size: 17px; font-weight: 500; margin-right: 22px; }
.btn:hover { text-decoration: none; filter: brightness(1.08); }
.link { font-size: 17px; }

/* landing */
.hero { text-align: center; padding-top: 140px !important; }
.hero h1 { font-size: clamp(44px, 8vw, 96px); margin: 0 0 .3em; }
.hero .lead { margin: 0 auto 1.6em; }
.section-head { text-align: center; margin-bottom: 56px !important; }
.section-head h2, .final h2 { font-size: clamp(32px, 5vw, 56px); margin: 0 0 .3em; }
.demo { background: var(--bg2); }
.split { display: grid; grid-template-columns: 1fr auto 1fr; gap: 20px; align-items: stretch; }
.panel { margin: 0; background: var(--card); border: 1px solid var(--line); border-radius: 22px; padding: 18px; box-shadow: 0 20px 50px -30px rgba(0,0,0,.25); min-width: 0; }
.panel figcaption { font: 600 13px var(--mono); color: var(--mut); display: flex; align-items: center; gap: 8px; margin: 2px 4px 14px; overflow-wrap: anywhere; }
.dot { width: 8px; height: 8px; border-radius: 50%; background: var(--line); flex: none; }
.dot.live { background: #30d158; box-shadow: 0 0 0 4px rgba(48,209,88,.18); }
.panel pre { margin: 0 0 10px; font-size: 13px; white-space: pre-wrap; word-break: break-word; }
.panel pre:last-child { margin-bottom: 0; }
.panel .resp { border-left: 3px solid #30d158; }
.panel .resp.err { border-left-color: #ff9f0a; }
.arrow { display: flex; align-items: center; justify-content: center; position: relative; width: 56px; }
.arrow::before { content: "→"; font-size: 32px; color: var(--accent); }
.arrow span { position: absolute; top: calc(50% + 28px); writing-mode: vertical-rl; font-size: 12px; color: var(--mut); white-space: nowrap; letter-spacing: .08em; }
.note { color: var(--mut); text-align: center; max-width: 760px !important; margin-top: 40px !important; font-size: 15px; }
.steps3 { list-style: none; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); gap: 48px; }
.steps3 h3 { font-size: 28px; margin: .3em 0 .4em; }
.steps3 p { color: var(--mut); margin: 0; }
.num { font: 600 15px var(--mono); color: var(--accent); }
.stats { background: var(--bg2); }
.grid4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.stat { background: var(--card); border-radius: 22px; padding: 32px 26px; border: 1px solid var(--line); }
.stat b { display: block; font-size: clamp(30px, 3.6vw, 44px); letter-spacing: -.03em; line-height: 1.1; margin-bottom: 12px; }
.stat span { color: var(--mut); font-size: 15px; }
.final { text-align: center; }

/* inner pages */
.page-head { margin-bottom: 56px; }
.page-head h1, .md h1, main > h1 { font-size: clamp(36px, 6vw, 64px); margin: 0 0 .3em; }
.cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 18px; margin-top: 32px; }
.card { background: var(--bg2); border-radius: 20px; padding: 26px; color: var(--fg); display: block; border: 1px solid transparent; transition: border-color .2s, transform .2s; }
a.card:hover { text-decoration: none; border-color: var(--line); transform: translateY(-2px); }
.card h3 { margin: .2em 0 .5em; font-size: 21px; }
.card p { color: var(--mut); margin: 0; font-size: 15px; }
.card small { color: var(--accent); font-weight: 600; }
.prose h2 { font-size: 32px; margin: 64px 0 18px; display: flex; gap: 14px; align-items: baseline; }
.prose h2 .num { font-size: 18px; }
.prose li { margin-bottom: .5em; }

/* docs */
.docs-wrap { display: grid; grid-template-columns: 240px minmax(0, 1fr); gap: 56px; max-width: 1240px; margin: 0 auto; padding: 48px 22px 96px; }
.sidebar { position: sticky; top: 76px; align-self: start; max-height: calc(100vh - 96px); overflow: auto; font-size: 14px; }
.sidebar a { display: block; padding: 6px 12px; color: var(--mut); border-radius: 8px; }
.sidebar a:hover { color: var(--fg); text-decoration: none; }
.sidebar a[aria-current] { background: var(--bg2); color: var(--fg); font-weight: 600; }
.sidebar h4 { margin: 22px 12px 6px; font-size: 12px; color: var(--mut); text-transform: uppercase; letter-spacing: .06em; }
.src { color: var(--mut); font-size: 13px; }
.notice { background: var(--bg2); border-left: 3px solid var(--accent); border-radius: 10px; padding: 14px 18px; margin: 16px 0 28px; font-size: 15px; }
.md { max-width: 820px; }
.md h2 { font-size: 30px; margin: 2em 0 .6em; padding-top: .4em; border-top: 1px solid var(--line); }
.md h3 { font-size: 21px; margin: 1.6em 0 .5em; }
.md table { border-collapse: collapse; display: block; overflow-x: auto; font-size: 14px; margin: 1.2em 0; }
.md th, .md td { border-bottom: 1px solid var(--line); padding: 10px 12px; text-align: left; vertical-align: top; }
.md th { font-weight: 600; }
.md blockquote { margin: 1.2em 0; padding: 4px 20px; border-left: 3px solid var(--line); color: var(--mut); }
.md img { max-width: 100%; }
.anchor { opacity: 0; margin-left: -.9em; padding-right: .25em; color: var(--mut); font-weight: 400; }
h1:hover .anchor, h2:hover .anchor, h3:hover .anchor { opacity: 1; text-decoration: none; }
.toc { border-top: 1px solid var(--line); margin-top: 56px; padding-top: 18px; font-size: 14px; max-width: 820px; }
.toc a { display: block; color: var(--mut); padding: 2px 0; }
.toc a.d3 { padding-left: 1.2em; }
footer { border-top: 1px solid var(--line); color: var(--mut); font-size: 12px; padding: 28px 22px; display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; max-width: 1120px; margin: 0 auto; }

/* syntax highlighting (highlight.js classes) */
.hljs-keyword, .hljs-selector-tag, .hljs-literal, .hljs-section, .hljs-name { color: var(--k); }
.hljs-string, .hljs-attr + .hljs-string, .hljs-regexp, .hljs-addition { color: var(--s); }
.hljs-number, .hljs-symbol, .hljs-bullet { color: var(--n); }
.hljs-comment, .hljs-quote, .hljs-meta { color: var(--c); }
.hljs-attr, .hljs-attribute, .hljs-variable, .hljs-type, .hljs-built_in { color: var(--t); }
.hljs-title, .hljs-function { color: var(--f); }
.hljs-strong { font-weight: 700; }
.hljs-emphasis { font-style: italic; }
.hljs-deletion { color: var(--s); }

/* scroll reveal — only when JS runs and motion is welcome */
@media (prefers-reduced-motion: no-preference) {
  .js .reveal { opacity: 0; transform: translateY(24px); transition: opacity .8s cubic-bezier(.2,.7,.2,1), transform .8s cubic-bezier(.2,.7,.2,1); }
  .js .reveal.in { opacity: 1; transform: none; }
}

/* responsive */
@media (max-width: 900px) {
  .split { grid-template-columns: minmax(0, 1fr); }
  .arrow { width: auto; height: 48px; }
  .arrow::before { content: "↓"; }
  .arrow span { position: static; writing-mode: horizontal-tb; margin-left: 12px; }
  .steps3 { grid-template-columns: 1fr; gap: 36px; }
  .grid4 { grid-template-columns: repeat(2, 1fr); }
  .docs-wrap { grid-template-columns: minmax(0, 1fr); gap: 24px; padding-top: 24px; }
  .sidebar { position: static; max-height: none; border-top: 1px solid var(--line); padding-top: 16px; order: 2; }
}
@media (max-width: 740px) {
  body { font-size: 16px; }
  .bar { gap: 12px; padding: 0 16px; }
  .menu { display: flex; order: 3; }
  .tools { margin-left: auto; }
  #nav { display: none; position: absolute; top: 52px; left: 0; right: 0; flex-direction: column; gap: 0; background: var(--bg); border-bottom: 1px solid var(--line); padding: 8px 16px 16px; font-size: 17px; }
  #nav a { padding: 12px 0; border-bottom: 1px solid var(--line); }
  .nav-open #nav { display: flex; }
  .page { padding: 48px 16px 72px; }
  .page.wide > main > section { padding: 80px 16px; }
  .hero { padding-top: 88px !important; }
  .lead { font-size: 19px; }
  .btn { margin: 0 12px 12px 0; }
  .grid4 { grid-template-columns: 1fr; }
  .panel { padding: 12px; border-radius: 18px; }
  .panel pre { font-size: 12px; padding: .9em 1em; }
  .docs-wrap { padding: 16px 16px 72px; }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; } }

/* development activity */
.activity { --add: #30d158; --del: #ff453a; }
.act-stats { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-bottom: 28px !important; text-align: center; }
.act-stats b { display: block; font-size: clamp(36px, 6vw, 64px); letter-spacing: -.035em; line-height: 1.05; font-variant-numeric: tabular-nums; }
.act-stats span { color: var(--mut); font-size: 15px; }
.act-stats .add b { color: var(--add); }
.act-stats .del b { color: var(--del); }
.chart-card { margin-top: 0; margin-bottom: 0; background: var(--card); border: 1px solid var(--line); border-radius: 22px; padding: 22px 18px 18px; }
.heatmap { --hm0: var(--bg2); --hm1: color-mix(in srgb, var(--accent) 28%, var(--card)); --hm2: color-mix(in srgb, var(--accent) 52%, var(--card)); --hm3: color-mix(in srgb, var(--accent) 76%, var(--card)); --hm4: var(--accent); }
.hm-title { margin: 0 0 12px; font-size: 15px; font-weight: 600; text-align: center; }
.hm-scroll { direction: rtl; overflow-x: auto; /* rtl: start scrolled to the newest week */ -webkit-overflow-scrolling: touch; padding-bottom: 4px; }
.hm-scroll:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }
.hm { --c: 11px; --g: 3px; display: grid; grid-template-columns: auto max-content; grid-template-rows: auto auto; gap: 4px 6px; direction: ltr; width: max-content; margin: 0 auto; font-size: 11px; color: var(--mut); }
.hm-months { grid-column: 2; display: grid; grid-template-columns: repeat(var(--weeks), var(--c)); column-gap: var(--g); white-space: nowrap; line-height: 1.2; }
.hm-days { grid-column: 1; grid-row: 2; display: grid; grid-template-rows: repeat(7, var(--c)); row-gap: var(--g); line-height: var(--c); text-align: right; }
.hm-grid { grid-column: 2; grid-row: 2; display: grid; grid-auto-flow: column; grid-auto-columns: var(--c); column-gap: var(--g); }
.hm-week { display: grid; grid-template-rows: repeat(7, var(--c)); row-gap: var(--g); }
.hm-cell { display: inline-block; width: var(--c, 11px); height: var(--c, 11px); border-radius: 2px; background: var(--hm0); outline: 1px solid color-mix(in srgb, var(--fg) 14%, transparent); outline-offset: -1px; }
.hm-cell.l1 { background: var(--hm1); } .hm-cell.l2 { background: var(--hm2); } .hm-cell.l3 { background: var(--hm3); } .hm-cell.l4 { background: var(--hm4); }
.hm-cell.today { outline: 1.5px solid var(--fg); }
.hm-legend { display: inline-flex; align-items: center; gap: 3px; }
.hm-legend .hm-cell { --c: 11px; }
.hm-sum { color: var(--fg); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }
.chart-card figcaption { display: flex; flex-wrap: wrap; gap: 8px 20px; justify-content: center; margin-top: 14px; font-size: 13px; color: var(--mut); }
.chart-card figcaption small { flex-basis: 100%; text-align: center; font-size: 12px; }
.act-table { margin-top: 18px !important; }
.act-table summary { cursor: pointer; color: var(--accent); font-size: 15px; text-align: center; list-style-position: inside; }
.act-table .table-wrap { margin-top: 14px; overflow-x: auto; background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 8px 18px; }
.activity-table { width: 100%; border-collapse: collapse; font-size: 14px; font-variant-numeric: tabular-nums; }
.activity-table th, .activity-table td { padding: 7px 10px; border-bottom: 1px solid var(--line); text-align: left; white-space: nowrap; }
.activity-table tbody tr:last-child > * { border-bottom: 0; }
.activity-table thead th { color: var(--mut); font-weight: 600; font-size: 12px; }
.activity-table tbody th { font-weight: 500; }
.activity-table .n { text-align: right; }
@media (max-width: 740px) {
  .act-stats { gap: 8px; }
  .act-stats span { font-size: 12px; }
  .chart-card { padding: 14px 6px 12px; border-radius: 16px; }
  .act-table .table-wrap { padding: 4px 8px; }
}

/* file tree (quick start) */
.tree { line-height: 1.75; font-size: 14px; overflow-x: auto; white-space: pre; }
.tree .g { color: var(--mut); opacity: .55; }
.tree .dir { color: var(--accent); font-weight: 600; }
.tree .file { color: var(--fg); }
.tree .cm { color: var(--mut); }
.tree-note { color: var(--mut); font-size: 14px; margin-top: -4px; }
@media (max-width: 740px) { .tree { font-size: 12.5px; } }
.sr { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0; }

/* spec version picker */
.versions { display: inline-flex; flex-wrap: wrap; gap: 2px; padding: 3px; border-radius: 999px; background: var(--bg2); border: 1px solid var(--line); margin-bottom: 14px; font-size: 13px; }
.versions a, .versions .cur { padding: 5px 14px; border-radius: 999px; color: var(--mut); white-space: nowrap; }
.versions a:hover { color: var(--fg); text-decoration: none; }
.versions .cur { background: var(--card); color: var(--fg); font-weight: 600; box-shadow: 0 1px 3px rgba(0,0,0,.12); }
.versions em { font-style: normal; font-size: 11px; color: var(--accent); margin-left: 4px; font-weight: 600; }
.notice.old { border-left-color: #ff9f0a; }
.notice.old strong { margin-right: 6px; }