/* Linear-style theme: near-black canvas, hairline borders, Inter, soft gradient headlines, indigo accent. */
:root {
  --bg: #08090a;
  --panel: #0f1011;
  --hover: #17181b;
  --border: #23252a;
  --text: #f7f8f8;
  --soft: #d0d6e0;
  --muted: #8a8f98;
  --faint: #62666d;
  --accent: #7170ff;
  --accent-bg: #5e6ad2;
  --red: #eb5757;
  --amber: #f2c94c;
  --sans: "Inter", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
  --side: 248px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--soft); font: 400 16px/1.6 var(--sans); font-feature-settings: "cv01", "ss03"; -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; border-radius: 6px; }
::selection { background: #5e6ad266; }

/* ------------------------------------------------ shell */
.app { display: grid; grid-template-columns: var(--side) minmax(0, 1fr); min-height: 100vh; }
.sidebar { position: sticky; top: 0; height: 100vh; overflow-y: auto; padding: 14px 10px; border-right: 1px solid var(--border); background: var(--bg); display: flex; flex-direction: column; gap: 14px; }
.brand { display: flex; align-items: center; gap: 9px; padding: 6px 8px; font-weight: 600; font-size: 14px; color: var(--text); }
.mark { display: grid; place-items: center; width: 22px; height: 22px; border-radius: 6px; background: linear-gradient(135deg, #7170ff, #4c4fd6); color: #fff; font-size: 12px; font-weight: 600; }
nav { display: flex; flex-direction: column; gap: 2px; font-size: 13.5px; }
nav a { display: flex; align-items: center; gap: 8px; padding: 5px 8px; border-radius: 6px; color: var(--muted); }
nav a:hover { background: var(--hover); color: var(--soft); }
nav a.on { background: var(--hover); color: var(--text); }
.nav-folder { margin-top: 10px; }
.nav-f { font-weight: 500; color: var(--soft); }
.nav-f svg { width: 15px; height: 15px; flex: none; color: var(--muted); }
.count { margin-left: auto; font-size: 12px; color: var(--faint); }
.nav-folder ul { list-style: none; margin: 2px 0 0 15px; padding: 0 0 0 8px; border-left: 1px solid var(--border); }
.nav-folder li a { padding: 4px 8px; line-height: 1.4; }
.side-links { margin-top: auto; display: flex; gap: 14px; padding: 8px; font-size: 12.5px; color: var(--faint); }
.side-links a:hover { color: var(--soft); }
.mobile-nav { display: none; }

.main { padding: 72px 40px 120px; }
.main > * { max-width: 680px; margin-inline: auto; }

/* ------------------------------------------------ headings */
.page-head { margin-bottom: 40px; }
.crumbs { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 18px; font-size: 13px; color: var(--faint); }
.crumbs a { color: var(--muted); }
.crumbs a:hover { color: var(--text); }
h1 {
  margin: 0 0 14px; font-size: clamp(32px, 5vw, 44px); line-height: 1.12; font-weight: 600; letter-spacing: -0.022em;
  background: linear-gradient(180deg, #ffffff 30%, #9ca0aa); -webkit-background-clip: text; background-clip: text; color: transparent;
}
.lede { margin: 0; font-size: 18px; line-height: 1.6; color: var(--muted); }
.meta { margin: 16px 0 0; font-size: 13px; color: var(--faint); }
.section-h { margin: 48px 0 8px; font-size: 13px; font-weight: 500; color: var(--muted); }

/* ------------------------------------------------ lists */
.rows, .folders { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--border); }
.rows li, .folders li { border-bottom: 1px solid var(--border); padding: 6px 0; }
.rows a, .folders a { display: flex; flex-direction: column; gap: 4px; padding: 12px 12px; margin: 0 -12px; border-radius: 8px; transition: background-color 120ms; }
.rows a:hover, .folders a:hover { background: var(--panel); }
.row-title { font-size: 16px; font-weight: 500; color: var(--text); }
.row-dek { font-size: 14.5px; color: var(--muted); line-height: 1.55; }
.row-meta { font-size: 12.5px; color: var(--faint); }

/* ------------------------------------------------ terminal opener */
.terminal { margin: 0 0 44px; border: 1px solid var(--border); border-radius: 12px; background: var(--panel); overflow: hidden; box-shadow: 0 0 0 1px #ffffff05, 0 24px 60px -30px #5e6ad255; }
.t-bar { display: flex; gap: 6px; padding: 10px 14px; border-bottom: 1px solid var(--border); }
.t-bar i { width: 9px; height: 9px; border-radius: 50%; background: #2b2d31; }
.t-body { padding: 16px 18px 18px; font: 400 13.5px/1.7 var(--mono); color: var(--soft); overflow-wrap: anywhere; }
.t-prompt { color: var(--faint); }
.t-out { display: block; margin-top: 8px; color: var(--muted); white-space: pre-wrap; }
.t-err { display: block; margin-top: 8px; color: var(--red); }

/* ------------------------------------------------ prose */
.prose { font-size: 16.5px; line-height: 1.75; }
.prose > * { margin: 0 0 20px; }
.prose h2 { margin: 52px 0 14px; font-size: 24px; line-height: 1.3; font-weight: 600; letter-spacing: -0.015em; color: var(--text); scroll-margin-top: 24px; }
.prose h3 { margin: 32px 0 10px; font-size: 18px; font-weight: 600; color: var(--text); }
.prose a { color: var(--accent); }
.prose a:hover { text-decoration: underline; text-underline-offset: 3px; }
.prose strong { color: var(--text); font-weight: 600; }
.prose ul, .prose ol { padding-left: 22px; }
.prose li { margin-bottom: 6px; }
.prose li::marker { color: var(--faint); }
.prose hr { border: 0; border-top: 1px solid var(--border); margin: 48px 0; }
.prose :not(pre) > code { font: 400 0.86em var(--mono); color: var(--text); background: var(--hover); border: 1px solid var(--border); padding: 1px 5px; border-radius: 5px; }

.code { position: relative; margin: 0 0 24px; border: 1px solid var(--border); border-radius: 10px; background: var(--panel); overflow: hidden; }
.code figcaption { padding: 7px 14px; font: 500 12px var(--sans); color: var(--faint); border-bottom: 1px solid var(--border); }
.code pre { margin: 0; padding: 14px 16px; overflow-x: auto; }
.code code { font: 400 13.5px/1.7 var(--mono); color: var(--soft); }
.copy { position: absolute; top: 5px; right: 6px; padding: 3px 9px; font: 500 12px var(--sans); color: var(--muted); background: var(--bg); border: 1px solid var(--border); border-radius: 6px; cursor: pointer; }
.copy:hover { color: var(--text); background: var(--hover); }

.prose blockquote { margin: 32px 0; padding: 2px 0 2px 18px; border-left: 2px solid var(--accent-bg); }
.prose blockquote p { margin: 0; font-size: 19px; line-height: 1.55; font-weight: 500; color: var(--text); letter-spacing: -0.01em; }

.prose .concept { padding: 16px 18px; border: 1px solid var(--border); border-radius: 10px; background: linear-gradient(180deg, #5e6ad214, transparent), var(--panel); }
.prose .concept p { margin: 0; }

.prose .timeline { list-style: none; padding: 0; margin: 28px 0 32px; }
.timeline li { position: relative; padding: 0 0 22px 26px; margin: 0; }
.timeline li::before { content: ""; position: absolute; left: 4px; top: 22px; bottom: -2px; width: 1px; background: var(--border); }
.timeline li:last-child::before { display: none; }
.timeline li::after { content: ""; position: absolute; left: 0; top: 7px; width: 9px; height: 9px; border-radius: 50%; border: 1px solid var(--faint); background: var(--bg); }
.timeline li.hot::after { border-color: var(--red); background: var(--red); box-shadow: 0 0 0 4px #eb575722; }
.timeline time { display: block; font-size: 13px; font-weight: 500; color: var(--muted); }

/* ------------------------------------------------ pager */
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--border); }
.pager a { display: flex; flex-direction: column; gap: 2px; padding: 14px 16px; border: 1px solid var(--border); border-radius: 10px; color: var(--text); font-weight: 500; font-size: 14.5px; }
.pager a:hover { background: var(--panel); }
.pager a span { font-size: 12.5px; font-weight: 400; color: var(--faint); }
.pager .next { text-align: right; grid-column: 2; }

/* ------------------------------------------------ mobile */
@media (max-width: 860px) {
  .app { display: block; }
  .sidebar { display: none; }
  .mobile-nav { display: block; position: sticky; top: 0; z-index: 5; background: #08090ae6; backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px); border-bottom: 1px solid var(--border); }
  .mobile-nav summary { display: flex; justify-content: space-between; align-items: center; padding: 10px 16px; list-style: none; cursor: pointer; }
  .mobile-nav summary::-webkit-details-marker { display: none; }
  .mobile-nav .brand { padding: 0; }
  .browse { font-size: 13px; color: var(--muted); padding: 4px 10px; border: 1px solid var(--border); border-radius: 6px; }
  .mobile-nav[open] .browse { color: var(--text); background: var(--hover); }
  .mobile-nav nav { padding: 4px 10px 14px; max-height: 70vh; overflow-y: auto; }
  .main { padding: 36px 16px 80px; }
  .lede { font-size: 17px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { grid-column: 1; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; } }