/* === AI Interview Wiki — Deep Profiles / Stripe Press flavored === */
:root {
  --purple: #635bff;
  --purple-light: #ece9ff;
  --purple-dark: #4039c4;
  --ink: #0a2540;
  --ink-soft: #425466;
  --ink-muted: #697386;
  --paper: #ffffff;
  --paper-warm: #faf9f7;
  --paper-cool: #f6f9fc;
  --line: #e3e8ee;
  --line-soft: #ebeef3;
  --accent: #635bff;
  --serif: "Fraunces", "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", Georgia, serif;
  --sans: "Inter", "Noto Sans SC", "PingFang SC", -apple-system, BlinkMacSystemFont, sans-serif;
  --mono: "JetBrains Mono", "SF Mono", "Menlo", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #f5f7fa; --ink-soft: #c1c9d2; --ink-muted: #8a94a6;
    --paper: #0a0e1a; --paper-warm: #111522; --paper-cool: #0d1220;
    --line: #1f2733; --line-soft: #161c28;
    --purple-light: #1f1b50;
  }
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 17px; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--sans);
  color: var(--ink-soft);
  background: var(--paper);
  line-height: 1.7;
  font-weight: 400;
  font-feature-settings: "kern", "liga", "calt";
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: inherit; text-decoration: none; }

/* --- Reading progress bar --- */
.progress {
  position: fixed; top: 0; left: 0; height: 3px;
  background: var(--accent); z-index: 1000;
  width: 0%; transition: width 0.05s linear;
}

/* --- Site header --- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: saturate(180%) blur(8px);
  -webkit-backdrop-filter: saturate(180%) blur(8px);
  border-bottom: 1px solid var(--line-soft);
  padding: 14px 0;
}
@media (prefers-color-scheme: dark) {
  .site-header { background: rgba(10,14,26,0.92); }
}
.header-inner {
  max-width: 1280px; margin: 0 auto; padding: 0 32px;
  display: flex; align-items: center; justify-content: space-between; gap: 20px;
}
.brand {
  font-family: var(--serif);
  font-variation-settings: "opsz" 24, "SOFT" 50, "WONK" 0;
  font-size: 18px; font-weight: 600; color: var(--ink); letter-spacing: -0.01em;
}
.brand .dot { color: var(--accent); }
.site-nav { display: flex; gap: 28px; font-size: 13px; font-weight: 500; }
.site-nav a {
  color: var(--ink-soft); padding: 4px 0;
  border-bottom: 1px solid transparent; transition: color .2s, border-color .2s;
}
.site-nav a:hover, .site-nav a.active { color: var(--accent); border-bottom-color: var(--accent); }

/* ====== INDEX PAGE ====== */
.index-page { max-width: 1280px; margin: 0 auto; padding: 80px 32px 120px; }
@media (max-width: 720px) { .index-page { padding: 56px 24px 80px; } }

.hero { margin-bottom: 96px; }
.hero-eyebrow {
  font-family: var(--sans); font-size: 13px; font-weight: 600;
  color: var(--accent); text-transform: uppercase; letter-spacing: 0.12em;
  margin-bottom: 24px;
}
.wordmark {
  font-family: var(--serif);
  font-variation-settings: "opsz" 144, "SOFT" 50, "WONK" 0;
  font-size: clamp(56px, 11vw, 120px);
  font-weight: 600; line-height: 1.05;
  letter-spacing: -0.02em; color: var(--ink);
  margin-bottom: 36px;
}
.wordmark .dot { color: var(--accent); margin-left: 4px; display: inline-block; animation: dot 2.4s cubic-bezier(.45,0,.55,1) infinite; }
@keyframes dot { 0%, 100% { transform: scale(1); } 50% { transform: scale(1.14); } }
@media (prefers-reduced-motion: reduce) { .wordmark .dot { animation: none; } }

.hero-sub {
  font-family: var(--serif);
  font-variation-settings: "opsz" 36, "SOFT" 40, "WONK" 0;
  font-size: clamp(19px, 2.4vw, 24px);
  font-weight: 400; font-style: italic;
  color: var(--ink-soft); max-width: 720px; line-height: 1.5;
  margin-bottom: 48px;
}
.hero-meta {
  display: flex; flex-wrap: wrap; gap: 32px 56px;
  padding: 28px 0 0; border-top: 1px solid var(--line);
  max-width: 800px;
}
.hm { display: flex; flex-direction: column; gap: 4px; }
.hm-l { font-size: 11px; font-weight: 600; color: var(--ink-muted); text-transform: uppercase; letter-spacing: .08em; }
.hm-v {
  font-family: var(--serif); font-variation-settings: "opsz" 28, "SOFT" 40, "WONK" 0;
  font-size: 22px; font-weight: 500; color: var(--ink);
}

/* category section + cards */
.cat-section { margin-bottom: 80px; }
.cat-header {
  display: flex; align-items: baseline; gap: 14px;
  margin-bottom: 28px; padding-bottom: 14px;
  border-bottom: 1px solid var(--line);
}
.cat-cn {
  font-family: var(--serif); font-variation-settings: "opsz" 36, "SOFT" 40, "WONK" 0;
  font-size: 26px; font-weight: 500; color: var(--ink); letter-spacing: -0.01em;
}
.cat-en {
  font-family: var(--sans); font-size: 13px; color: var(--ink-muted);
  font-weight: 500; letter-spacing: .04em;
}
.cat-count {
  margin-left: auto; font-family: var(--mono); font-size: 12px;
  color: var(--ink-muted); padding: 2px 8px;
  border: 1px solid var(--line); border-radius: 12px;
}

.cards-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.card {
  display: flex; flex-direction: column;
  background: var(--paper); border: 1px solid var(--line);
  border-radius: 12px; padding: 24px 22px 18px;
  position: relative; overflow: hidden;
  transition: transform .32s cubic-bezier(.22,1,.36,1),
              box-shadow .32s cubic-bezier(.22,1,.36,1),
              border-color .25s ease;
  min-height: 240px;
}
.card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 3px; background: var(--accent);
  transform: scaleX(.4); transform-origin: left;
  opacity: 0; transition: opacity .3s, transform .5s cubic-bezier(.22,1,.36,1);
}
.card:hover {
  border-color: rgba(10,37,64,0.14); transform: translateY(-3px);
  box-shadow: 0 1px 2px rgba(10,37,64,.04),
              0 12px 28px -14px rgba(10,37,64,.14),
              0 28px 48px -28px rgba(10,37,64,.08);
}
.card:hover::before { opacity: 1; transform: scaleX(1); }
@media (prefers-color-scheme: dark) {
  .card:hover {
    border-color: rgba(245,247,250,.18);
    box-shadow: 0 1px 2px rgba(0,0,0,.35), 0 12px 32px -14px rgba(0,0,0,.55), 0 28px 48px -28px rgba(0,0,0,.35);
  }
}

.card-kind {
  font-family: var(--sans); font-size: 11px; font-weight: 600;
  color: var(--accent); text-transform: uppercase; letter-spacing: .12em;
  margin-bottom: 12px;
}
.card-name {
  font-family: var(--serif); font-variation-settings: "opsz" 36, "SOFT" 40, "WONK" 0;
  font-size: 22px; font-weight: 500; line-height: 1.2;
  letter-spacing: -0.012em; color: var(--ink);
  margin-bottom: 6px;
}
.card-en {
  font-family: var(--sans); font-size: 12px; color: var(--ink-muted);
  font-weight: 500; letter-spacing: .03em; margin-bottom: 12px;
}
.card-gist {
  font-family: var(--sans); font-size: 14px; color: var(--ink-soft);
  line-height: 1.55; margin-bottom: 16px;
  display: -webkit-box; -webkit-line-clamp: 4; -webkit-box-orient: vertical; overflow: hidden;
}
.card-meta {
  margin-top: auto;
  font-family: var(--mono); font-size: 11px; color: var(--ink-muted);
  padding-top: 12px; border-top: 1px solid var(--line-soft);
}

.library-link {
  display: flex; align-items: center; justify-content: space-between;
  padding: 28px 32px; background: var(--paper-warm);
  border: 1px solid var(--line); border-radius: 12px;
  transition: border-color .2s, transform .2s;
}
.library-link:hover { border-color: var(--accent); transform: translateY(-2px); }
.lib-cn {
  font-family: var(--serif); font-variation-settings: "opsz" 36, "SOFT" 40;
  font-size: 22px; font-weight: 500; color: var(--ink); margin-bottom: 6px;
}
.lib-en { font-family: var(--mono); font-size: 12px; color: var(--ink-muted); }
.lib-arrow {
  font-family: var(--serif); font-size: 32px; color: var(--accent);
  transition: transform .2s;
}
.library-link:hover .lib-arrow { transform: translateX(6px); }

/* ====== READING PAGE ====== */
.reading-container {
  max-width: 1280px; margin: 0 auto; padding: 60px 32px 80px;
  display: grid; grid-template-columns: 240px 1fr; gap: 80px;
}
@media (max-width: 1000px) {
  .reading-container { grid-template-columns: 1fr; gap: 40px; padding: 40px 24px 80px; }
}

.toc {
  position: sticky; top: 80px; align-self: start;
  max-height: calc(100vh - 100px); overflow-y: auto;
  font-size: 13px; padding-right: 16px;
}
.toc::-webkit-scrollbar { width: 4px; }
.toc::-webkit-scrollbar-thumb { background: var(--line); border-radius: 2px; }
.toc-title {
  font-family: var(--sans); font-size: 11px; font-weight: 700;
  color: var(--ink-muted); text-transform: uppercase; letter-spacing: 0.14em;
  margin-bottom: 16px; padding-bottom: 12px; border-bottom: 2px solid var(--ink);
}
.toc-list { list-style: none; }
.toc-list > li { margin-bottom: 2px; }
.toc-item-row {
  display: flex; border-left: 2px solid var(--line);
  transition: border-color .2s;
}
.toc-item-row:hover { border-left-color: var(--purple-light); }
.toc-item-row > a {
  flex: 1; padding: 6px 4px 6px 12px;
  color: var(--ink-soft); font-size: 13px; line-height: 1.4; font-weight: 500;
  transition: color .2s;
}
.toc-item-row > a:hover, .toc-item-row > a.active {
  color: var(--accent); font-weight: 600;
}
.toc-item-row > a.active { border-left: 0; }
.toc-sub { list-style: none; margin: 4px 0 8px; padding: 0; }
.toc-sub li { margin-bottom: 1px; }
.toc-sub a {
  display: block; padding: 4px 8px 4px 28px;
  color: var(--ink-muted); font-size: 12px; line-height: 1.35;
  border-left: 2px solid transparent; transition: all .2s;
}
.toc-sub a:hover, .toc-sub a.active {
  color: var(--accent); border-left-color: var(--accent);
}

.content {
  max-width: 720px; font-size: 18px; color: var(--ink-soft);
}
.article-eyebrow {
  font-family: var(--sans); font-size: 13px; font-weight: 600;
  color: var(--accent); text-transform: uppercase; letter-spacing: .12em;
  margin-bottom: 20px;
}
.article-title {
  font-family: var(--serif);
  font-variation-settings: "opsz" 90, "SOFT" 50, "WONK" 1;
  font-size: clamp(36px, 6vw, 56px);
  font-weight: 500; line-height: 1.08;
  letter-spacing: -0.025em; color: var(--ink); margin-bottom: 24px;
}
.article-sub {
  font-family: var(--serif); font-variation-settings: "opsz" 36, "SOFT" 40;
  font-size: clamp(18px, 2.4vw, 22px); font-style: italic;
  color: var(--ink-soft); margin-bottom: 48px; line-height: 1.5;
}

.content h2 {
  font-family: var(--serif); font-variation-settings: "opsz" 64, "SOFT" 40;
  font-size: clamp(28px, 4.5vw, 36px); font-weight: 500; line-height: 1.18;
  letter-spacing: -0.015em; color: var(--ink);
  margin: 72px 0 24px; padding-bottom: 14px;
  border-bottom: 1px solid var(--line); scroll-margin-top: 80px;
}
.content h2:first-of-type { margin-top: 0; }
.content h3 {
  font-family: var(--serif); font-variation-settings: "opsz" 36, "SOFT" 30;
  font-size: clamp(20px, 2.8vw, 26px); font-weight: 500; line-height: 1.25;
  letter-spacing: -0.008em; color: var(--ink);
  margin: 48px 0 16px; scroll-margin-top: 80px;
}
.content p { margin-bottom: 22px; font-size: 18px; line-height: 1.75; color: var(--ink-soft); }
.content p strong { color: var(--ink); font-weight: 600; }
.content em { font-style: italic; }
.content a {
  color: var(--accent);
  border-bottom: 1px solid transparent; transition: border-color .2s;
}
.content a:hover { border-bottom-color: var(--accent); }
.content a.xref {
  border-bottom: 1px dotted var(--accent);
}
.content ul, .content ol { margin: 0 0 24px 24px; }
.content li { margin-bottom: 10px; line-height: 1.7; }
.content hr { border: 0; height: 1px; background: var(--line); margin: 48px 0; }
.content code {
  font-family: var(--mono); font-size: 14px;
  padding: 2px 6px; background: var(--paper-cool);
  border: 1px solid var(--line-soft); border-radius: 4px;
  color: var(--purple-dark);
}

/* Bilingual blockquote — the signature element */
blockquote.bilingual {
  position: relative;
  margin: 36px 0 36px -16px;
  padding: 28px 32px;
  background: var(--paper-warm);
  border-left: 4px solid var(--accent);
  border-radius: 0 8px 8px 0;
}
blockquote.bilingual::before {
  content: '"';
  position: absolute; top: -12px; left: 16px;
  font-family: var(--serif); font-size: 80px; line-height: 1;
  color: var(--accent); opacity: 0.28; font-weight: 700;
}
blockquote.bilingual .en {
  font-family: var(--serif); font-variation-settings: "opsz" 24, "SOFT" 50;
  font-style: italic; font-size: 20px; line-height: 1.5;
  color: var(--ink); font-weight: 450; margin-bottom: 12px;
  letter-spacing: -0.003em;
}
blockquote.bilingual .zh {
  font-family: var(--sans); font-size: 16px; line-height: 1.65;
  color: var(--ink-soft); margin-bottom: 14px;
}
blockquote.bilingual .src {
  font-family: var(--sans); font-size: 12px;
  text-transform: uppercase; letter-spacing: 0.08em;
  color: var(--ink-muted); font-weight: 600;
}
blockquote.bilingual .src::before { content: '— '; color: var(--accent); }

blockquote.plain {
  font-family: var(--serif); font-variation-settings: "opsz" 24, "SOFT" 50;
  font-style: italic; font-size: 19px; line-height: 1.55;
  color: var(--ink); padding: 16px 0 16px 24px;
  margin: 24px 0; border-left: 3px solid var(--accent);
}

/* --- Related (footer of insight page) --- */
.related {
  background: var(--paper-cool); border-top: 1px solid var(--line);
  padding: 60px 32px;
}
.related-inner { max-width: 1280px; margin: 0 auto; }
.related-header {
  font-family: var(--sans); font-size: 13px; font-weight: 700;
  color: var(--ink-muted); text-transform: uppercase; letter-spacing: 0.14em;
  margin-bottom: 24px;
}
.related-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
}
.rel-card {
  padding: 16px 18px; background: var(--paper); border: 1px solid var(--line);
  border-radius: 10px; transition: border-color .2s, transform .2s;
  display: block;
}
.rel-card:hover { border-color: var(--accent); transform: translateY(-2px); }
.rel-kind {
  font-size: 10px; font-weight: 600; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--accent); margin-bottom: 8px;
}
.rel-name {
  font-family: var(--serif); font-variation-settings: "opsz" 24, "SOFT" 40;
  font-size: 16px; font-weight: 500; color: var(--ink); line-height: 1.3;
}

/* ====== LIBRARY ====== */
.library-page { max-width: 1100px; margin: 0 auto; padding: 80px 32px 120px; }
.lib-hero { margin-bottom: 60px; }
.lib-controls {
  display: flex; gap: 12px; margin-top: 36px; flex-wrap: wrap;
  align-items: center;
}
.lib-controls input[type="search"] {
  flex: 1; min-width: 240px;
  font-family: var(--sans); font-size: 14px;
  background: var(--paper); color: var(--ink);
  border: 1px solid var(--line); border-radius: 8px;
  padding: 10px 14px;
  transition: border-color .2s;
}
.lib-controls input[type="search"]:focus { outline: none; border-color: var(--accent); }
.lib-controls select {
  font-family: var(--sans); font-size: 13px;
  background: var(--paper); color: var(--ink);
  border: 1px solid var(--line); border-radius: 8px;
  padding: 9px 12px; cursor: pointer;
}
.lib-count {
  font-family: var(--mono); font-size: 12px; color: var(--ink-muted);
  margin-left: auto;
}

.lib-list { display: flex; flex-direction: column; gap: 0; }
.lib-row {
  display: grid; grid-template-columns: 100px 1fr; gap: 24px;
  padding: 24px 0; border-bottom: 1px solid var(--line-soft);
  cursor: pointer; transition: background .15s;
}
.lib-row:hover { background: var(--paper-warm); }
.lib-row-date {
  font-family: var(--mono); font-size: 12px; color: var(--ink-muted);
  padding-top: 2px;
}
.lib-row-title {
  font-family: var(--serif); font-variation-settings: "opsz" 28, "SOFT" 40;
  font-size: 19px; font-weight: 500; color: var(--ink); line-height: 1.3;
  margin-bottom: 6px;
}
.lib-row-gist {
  font-size: 14px; color: var(--ink-soft); line-height: 1.55; margin-bottom: 10px;
}
.lib-row-meta {
  font-family: var(--mono); font-size: 11px; color: var(--ink-muted);
  display: flex; gap: 8px;
}
.lib-row-meta .dot { opacity: .4; }
.lib-empty { padding: 80px 0; text-align: center; color: var(--ink-muted); }

/* Drawer */
.scrim {
  position: fixed; inset: 0; background: rgba(10,37,64,0.45); z-index: 200;
  opacity: 0; pointer-events: none; transition: opacity .2s;
}
.scrim.open { opacity: 1; pointer-events: auto; }
.drawer {
  position: fixed; top: 0; right: 0; height: 100%;
  width: min(760px, 96vw); background: var(--paper);
  border-left: 1px solid var(--line); z-index: 210;
  transform: translateX(100%); transition: transform .25s cubic-bezier(.22,1,.36,1);
  display: flex; flex-direction: column;
}
.drawer.open { transform: translateX(0); }
.drawer-head {
  padding: 28px 36px 22px; border-bottom: 1px solid var(--line);
  position: relative;
}
.drawer-eyebrow {
  font-size: 11px; font-weight: 600; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--accent); margin-bottom: 10px;
}
.drawer-title {
  font-family: var(--serif); font-variation-settings: "opsz" 48, "SOFT" 40;
  font-size: 22px; font-weight: 500; color: var(--ink); line-height: 1.3;
  padding-right: 32px; margin-bottom: 14px;
}
.drawer-meta {
  font-family: var(--mono); font-size: 12px; color: var(--ink-muted);
}
.drawer-meta a { color: var(--accent); }
.close {
  position: absolute; top: 24px; right: 28px;
  background: transparent; border: 0; cursor: pointer;
  color: var(--ink-muted); font-size: 28px; line-height: 1;
}
.close:hover { color: var(--ink); }

.drawer-body { overflow-y: auto; padding: 28px 36px 80px; }
.dsec { margin-bottom: 36px; }
.dsec h3 {
  font-family: var(--sans); font-size: 12px; font-weight: 700;
  color: var(--accent); text-transform: uppercase; letter-spacing: 0.12em;
  margin-bottom: 14px;
}
.dsec p { font-size: 15px; line-height: 1.7; color: var(--ink-soft); }
.tk { list-style: none; padding: 0; }
.tk li {
  padding: 9px 0 9px 18px; position: relative; color: var(--ink-soft);
  border-bottom: 1px solid var(--line-soft); font-size: 14.5px; line-height: 1.55;
}
.tk li:last-child { border-bottom: none; }
.tk li::before {
  content: "·"; position: absolute; left: 0; color: var(--accent); font-weight: 700;
}
.hl {
  font-family: var(--serif); font-variation-settings: "opsz" 24, "SOFT" 50;
  font-style: italic; font-size: 15.5px; line-height: 1.55;
  color: var(--ink-soft);
  border-left: 3px solid var(--accent); padding: 8px 0 8px 16px; margin-bottom: 14px;
}
details.qa {
  border-bottom: 1px solid var(--line-soft); padding: 4px 0;
}
details.qa[open] { background: var(--paper-warm); margin: 0 -8px; padding: 4px 8px; border-radius: 6px; }
details.qa summary {
  cursor: pointer; padding: 10px 0;
  font-size: 14px; font-weight: 500; color: var(--ink);
  list-style: none;
}
details.qa summary::marker, details.qa summary::-webkit-details-marker { display: none; }
details.qa summary::before {
  content: '+ '; color: var(--accent); font-weight: 600; margin-right: 6px;
}
details.qa[open] summary::before { content: '− '; }
.qa-a { padding: 4px 0 14px 18px; font-size: 13.5px; color: var(--ink-soft); line-height: 1.65; }
.kw { display: flex; flex-wrap: wrap; gap: 6px; }
.kw-chip {
  font-family: var(--sans); font-size: 11px;
  background: var(--paper-warm); border: 1px solid var(--line);
  color: var(--ink-soft); padding: 3px 9px; border-radius: 20px;
}

/* ====== Footer ====== */
.site-footer {
  background: var(--paper-cool); border-top: 1px solid var(--line);
  padding: 36px 0; text-align: center;
  font-size: 13px; color: var(--ink-muted);
}
.footer-inner { max-width: 1280px; margin: 0 auto; padding: 0 32px; }
.site-footer a { color: var(--accent); border-bottom: 1px solid transparent; transition: border-color .2s; }
.site-footer a:hover { border-bottom-color: var(--accent); }
.footer-meta { margin-top: 8px; font-family: var(--mono); font-size: 11px; opacity: .7; }