/* ==========================================================================
   开元棋牌官网 - 全站样式
   Design System: AI Learning Lab + Game Review Studio + Training Planner
   ========================================================================== */

:root {
  /* 主色：暖白 / 深墨蓝 / 教育青绿 / 训练蓝 / 进度金 */
  --color-bg: #FAF8F2;
  --color-bg-alt: #F1ECDF;
  --color-surface: #FFFFFF;
  --color-ink: #182A4A;
  --color-ink-soft: #3A4A6B;
  --color-text: #24304C;
  --color-text-mute: #5E6B87;
  --color-border: #E5DFD0;

  --color-teal: #146B5E;      /* 教育青绿：平台 / 教学 */
  --color-teal-bg: #E4F1EC;
  --color-blue: #2B5D9E;      /* 训练蓝：训练 / 陪练 */
  --color-blue-bg: #E7EEF8;
  --color-gold: #A8730F;      /* 进度金：进度 / 高优先级 */
  --color-gold-bg: #F8EEDA;
  --color-rose: #93304F;      /* 复盘 / 错误分析 */
  --color-rose-bg: #F7E8ED;
  --color-amber: #966A16;     /* 题库 / 残局训练 */
  --color-amber-bg: #F7EEDC;
  --color-forest: #37623A;    /* 课程 / 技能树 */
  --color-forest-bg: #E9F1E7;
  --color-purple: #5A4C93;    /* AI / 大模型 */
  --color-purple-bg: #ECE9F6;
  --color-indigo: #38507E;    /* App */
  --color-indigo-bg: #E7ECF5;

  --color-warn-bg: #FFF4E2;
  --color-warn-border: #E5C27C;
  --color-warn-text: #6B4B10;

  --shadow-sm: 0 1px 2px rgba(24, 42, 74, 0.06);
  --shadow-md: 0 6px 20px rgba(24, 42, 74, 0.08);
  --shadow-lg: 0 16px 40px rgba(24, 42, 74, 0.12);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --container-w: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  line-height: 1.75;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img, svg { max-width: 100%; height: auto; display: block; }
a { color: var(--color-teal); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { color: var(--color-ink); line-height: 1.35; margin: 0 0 .6em; font-weight: 700; }
p { margin: 0 0 1em; }
ul, ol { margin: 0 0 1em; padding-left: 1.4em; }
.container { max-width: var(--container-w); margin: 0 auto; padding: 0 20px; }
.visually-hidden { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(250, 248, 242, 0.97);
  border-bottom: 1px solid var(--color-border);
}
.nav-container {
  max-width: var(--container-w); margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; justify-content: space-between;
  height: 66px;
}
.nav-brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: var(--color-ink); font-size: 1.1rem; }
.nav-brand:hover { text-decoration: none; }
.nav-brand img { width: 34px; height: 34px; }
.nav-menu { display: flex; align-items: center; gap: 2px; list-style: none; margin: 0; padding: 0; flex-wrap: wrap; }
.nav-menu a {
  display: inline-block; padding: 9px 10px; border-radius: var(--radius-sm);
  color: var(--color-ink-soft); font-size: .85rem; font-weight: 500; white-space: nowrap;
}
.nav-menu a:hover, .nav-menu a[aria-current="page"] {
  background: var(--color-teal-bg); color: var(--color-teal); text-decoration: none;
}
.nav-toggle {
  display: none; width: 40px; height: 40px; border: 1px solid var(--color-border);
  background: var(--color-surface); border-radius: var(--radius-sm); cursor: pointer;
  position: relative;
}
.nav-toggle span, .nav-toggle::before, .nav-toggle::after {
  content: ""; position: absolute; left: 9px; right: 9px; height: 2px; background: var(--color-ink);
}
.nav-toggle::before { top: 13px; }
.nav-toggle span { top: 19px; }
.nav-toggle::after { top: 25px; }

/* ---------- Hero ---------- */
.hero {
  padding: 56px 0 44px;
  background: linear-gradient(180deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
  border-bottom: 1px solid var(--color-border);
}
.hero-inner { display: grid; grid-template-columns: 1.1fr .9fr; gap: 40px; align-items: center; }
.hero-eyebrow {
  display: inline-block; font-size: .82rem; font-weight: 700; letter-spacing: .04em;
  color: var(--color-teal); background: var(--color-teal-bg); padding: 5px 12px; border-radius: 999px; margin-bottom: 14px;
}
.hero-title { font-size: 2.05rem; margin-bottom: .5em; }
.hero-subtitle { font-size: 1.03rem; color: var(--color-text-mute); max-width: 58ch; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 18px 0; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 20px; }
.hero-art { width: 100%; }

.btn {
  display: inline-flex; align-items: center; gap: 8px; padding: 11px 22px; border-radius: 999px;
  font-weight: 700; font-size: .95rem; border: 1px solid transparent; cursor: pointer; font-family: inherit;
}
.btn-primary { background: var(--color-ink); color: #fff; }
.btn-primary:hover { background: #0F1E38; text-decoration: none; }
.btn-secondary { background: var(--color-surface); border-color: var(--color-border); color: var(--color-ink); }
.btn-secondary:hover { border-color: var(--color-teal); color: var(--color-teal); text-decoration: none; }

/* ---------- Tag / Badge ---------- */
.tag {
  display: inline-block; font-size: .78rem; font-weight: 600; padding: 4px 10px; border-radius: 999px;
  background: var(--color-bg-alt); color: var(--color-ink-soft); border: 1px solid var(--color-border);
}
.tag-teal { background: var(--color-teal-bg); color: var(--color-teal); border-color: transparent; }
.tag-blue { background: var(--color-blue-bg); color: var(--color-blue); border-color: transparent; }
.tag-rose { background: var(--color-rose-bg); color: var(--color-rose); border-color: transparent; }
.tag-amber { background: var(--color-amber-bg); color: var(--color-amber); border-color: transparent; }
.tag-forest { background: var(--color-forest-bg); color: var(--color-forest); border-color: transparent; }
.tag-purple { background: var(--color-purple-bg); color: var(--color-purple); border-color: transparent; }
.tag-indigo { background: var(--color-indigo-bg); color: var(--color-indigo); border-color: transparent; }
.tag-gold { background: var(--color-gold-bg); color: var(--color-gold); border-color: transparent; }
.tag-list { display: flex; flex-wrap: wrap; gap: 8px; }

/* ---------- Section ---------- */
.section { padding: 54px 0; }
.section-alt { background: var(--color-bg-alt); }
.section-head { max-width: 76ch; margin-bottom: 30px; }
.section-eyebrow { color: var(--color-teal); font-weight: 700; font-size: .82rem; letter-spacing: .04em; text-transform: uppercase; margin-bottom: 8px; display: block; }
.section-title { font-size: 1.6rem; }
.section-lead { color: var(--color-text-mute); font-size: 1.02rem; }

/* ---------- Grid / Cards ---------- */
.grid { display: grid; gap: 20px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-md);
  padding: 22px; box-shadow: var(--shadow-sm);
}
.card-icon { width: 42px; height: 42px; margin-bottom: 14px; }
.card-title { font-size: 1.03rem; margin-bottom: .4em; }
.card-desc { color: var(--color-text-mute); font-size: .92rem; margin-bottom: 0; }
.card-num {
  display: inline-flex; align-items: center; justify-content: center; width: 28px; height: 28px;
  border-radius: 50%; background: var(--color-ink); color: #fff; font-size: .82rem; font-weight: 700;
  margin-bottom: 10px;
}

/* ---------- Article block (flagship articles) ---------- */
.article-block {
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  padding: 30px 32px; margin-bottom: 24px; box-shadow: var(--shadow-sm);
}
.article-meta { display: flex; align-items: center; gap: 10px; font-size: .84rem; color: var(--color-text-mute); margin-bottom: 10px; flex-wrap: wrap; }
.article-title { font-size: 1.3rem; margin-bottom: .5em; }
.article-body { color: var(--color-text); }
.article-body p { margin-bottom: 1em; }
.article-figure { margin: 20px 0; text-align: center; }
.article-figure figcaption { font-size: .82rem; color: var(--color-text-mute); margin-top: 8px; }

.article-mini {
  border: 1px solid var(--color-border); border-radius: var(--radius-md); padding: 18px 20px;
  background: var(--color-surface); margin-bottom: 16px;
}
.article-mini .article-title { font-size: 1.03rem; }
.article-mini .article-body { font-size: .93rem; color: var(--color-text-mute); }

/* ---------- 展开阅读全文（原生 details/summary，全文本一直在 HTML 中，可被搜索引擎读取） ---------- */
details.article-expand summary {
  cursor: pointer; list-style: none; color: var(--color-teal); font-weight: 700; font-size: .92rem;
  margin-top: 6px; display: inline-flex; align-items: center; gap: 6px;
}
details.article-expand summary::-webkit-details-marker { display: none; }
details.article-expand summary::after { content: "展开阅读全文 ↓"; }
details.article-expand[open] summary::after { content: "收起全文 ↑"; }
details.article-expand .article-full { margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--color-border); }

/* ---------- Chain / Flow diagram ---------- */
.chain-diagram { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 20px 0; }
.chain-step {
  background: var(--color-teal-bg); color: var(--color-teal); border-radius: var(--radius-sm);
  padding: 8px 14px; font-size: .86rem; font-weight: 700; white-space: nowrap;
}
.chain-step.alt { background: var(--color-blue-bg); color: var(--color-blue); }
.chain-step.warn { background: var(--color-rose-bg); color: var(--color-rose); }
.chain-arrow { color: var(--color-text-mute); font-size: 1rem; }

/* ---------- Funnel (Review Compression Funnel / Puzzle Pipeline 纵向压缩流) ---------- */
.funnel { display: grid; gap: 10px; margin: 22px 0; }
.funnel-row {
  display: grid; grid-template-columns: 120px 1fr auto; align-items: center; gap: 14px;
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-md);
  padding: 12px 16px;
}
.funnel-label { font-weight: 700; font-size: .88rem; color: var(--color-ink); }
.funnel-bar-wrap { background: var(--color-bg-alt); border-radius: 999px; height: 14px; overflow: hidden; }
.funnel-bar { height: 100%; background: linear-gradient(90deg, var(--color-teal), var(--color-blue)); border-radius: 999px; }
.funnel-count { font-size: .82rem; color: var(--color-text-mute); white-space: nowrap; }

/* ---------- Ladder (Hint Ladder / Skill Tree 阶梯) ---------- */
.ladder { display: grid; gap: 14px; }
.ladder-step {
  display: grid; grid-template-columns: 44px 1fr; gap: 14px; align-items: start;
  border-left: 3px solid var(--color-border); padding: 4px 0 4px 18px; position: relative;
}
.ladder-step .ladder-num {
  width: 34px; height: 34px; border-radius: 50%; background: var(--color-ink); color: #fff;
  display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: .9rem;
  margin-left: -21px;
}
.ladder-step h4 { margin-bottom: .3em; font-size: 1rem; }
.ladder-step p { color: var(--color-text-mute); font-size: .9rem; margin-bottom: 0; }
.ladder-step.is-active { border-left-color: var(--color-teal); }
.ladder-step.is-active .ladder-num { background: var(--color-teal); }

/* ---------- Hint Ladder 互动演示 ---------- */
.hint-demo { display: grid; gap: 16px; }
.hint-demo .tabs-bar { margin-bottom: 0; }
.hint-output {
  background: var(--color-teal-bg); border: 1px solid var(--color-border); border-radius: var(--radius-md);
  padding: 18px 20px; color: var(--color-ink); font-size: .95rem; min-height: 64px;
}
.hint-progress { display: flex; gap: 4px; }
.hint-progress span { flex: 1; height: 6px; border-radius: 999px; background: var(--color-bg-alt); }
.hint-progress span.is-filled { background: var(--color-teal); }

/* ---------- Skill Profile / Radar ---------- */
.radar-wrap { display: flex; gap: 24px; flex-wrap: wrap; align-items: center; }
.radar-legend { list-style: none; padding: 0; margin: 0; font-size: .85rem; color: var(--color-text-mute); }
.radar-legend li { margin-bottom: 6px; display: flex; align-items: center; gap: 8px; }
.legend-dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }

.confidence-badge {
  display: inline-flex; align-items: center; gap: 8px; padding: 6px 14px; border-radius: 999px;
  font-size: .82rem; font-weight: 700; background: var(--color-bg-alt); color: var(--color-ink-soft);
  border: 1px solid var(--color-border);
}
.confidence-badge.developing { background: var(--color-gold-bg); color: var(--color-gold); }
.confidence-badge.stable { background: var(--color-blue-bg); color: var(--color-blue); }
.confidence-badge.strong { background: var(--color-teal-bg); color: var(--color-teal); }

/* ---------- Priority board（训练优先级） ---------- */
.priority-board { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin: 20px 0; }
.priority-col { border-radius: var(--radius-md); padding: 16px; border: 1px solid var(--color-border); background: var(--color-surface); }
.priority-col h4 { font-size: .92rem; margin-bottom: 10px; display: flex; align-items: center; gap: 8px; }
.priority-col.high { border-top: 3px solid var(--color-rose); }
.priority-col.medium { border-top: 3px solid var(--color-gold); }
.priority-col.later { border-top: 3px solid var(--color-text-mute); }
.priority-item { font-size: .85rem; color: var(--color-text-mute); padding: 8px 0; border-bottom: 1px dashed var(--color-border); }
.priority-item:last-child { border-bottom: none; }

/* ---------- Skill Tree ---------- */
.skill-tree { display: grid; gap: 12px; }
.tree-level { display: grid; grid-template-columns: 160px 1fr; gap: 14px; align-items: start; }
.tree-level-label { font-size: .82rem; font-weight: 700; color: var(--color-forest); padding-top: 10px; }
.tree-nodes { display: flex; flex-wrap: wrap; gap: 10px; }
.tree-node {
  background: var(--color-forest-bg); color: var(--color-forest); border-radius: var(--radius-sm);
  padding: 10px 14px; font-size: .85rem; font-weight: 600; border: 1px solid transparent;
}
.tree-node.locked { background: var(--color-bg-alt); color: var(--color-text-mute); border-style: dashed; border-color: var(--color-border); }

/* ---------- Engine + LLM Grounding 架构图 ---------- */
.arch-diagram { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin: 20px 0; }
.arch-col { border-radius: var(--radius-md); padding: 20px; border: 1px solid var(--color-border); }
.arch-col.engine { background: var(--color-blue-bg); }
.arch-col.llm { background: var(--color-purple-bg); }
.arch-col h4 { font-size: .95rem; margin-bottom: 10px; }
.arch-col.engine h4 { color: var(--color-blue); }
.arch-col.llm h4 { color: var(--color-purple); }
.arch-col ul { padding-left: 1.2em; font-size: .87rem; color: var(--color-text); margin-bottom: 0; }

/* ---------- Error Chain ---------- */
.error-chain { display: grid; gap: 12px; margin: 20px 0; }
.error-chain-step {
  display: grid; grid-template-columns: 120px 1fr; gap: 14px; align-items: center;
  border-radius: var(--radius-md); padding: 12px 16px; border: 1px solid var(--color-border);
}
.error-chain-step.root { background: var(--color-amber-bg); }
.error-chain-step.factor { background: var(--color-bg-alt); }
.error-chain-step.final { background: var(--color-rose-bg); }
.error-chain-tag { font-size: .8rem; font-weight: 700; }
.error-chain-step.root .error-chain-tag { color: var(--color-amber); }
.error-chain-step.factor .error-chain-tag { color: var(--color-ink-soft); }
.error-chain-step.final .error-chain-tag { color: var(--color-rose); }

/* ---------- FAQ ---------- */
.faq-item { border-bottom: 1px solid var(--color-border); padding: 4px 0; }
.faq-item:last-child { border-bottom: none; }
.faq-question {
  width: 100%; text-align: left; background: none; border: none; cursor: pointer;
  padding: 16px 30px 16px 0; font-size: 1rem; font-weight: 700; color: var(--color-ink);
  position: relative; font-family: inherit;
}
.faq-question::after {
  content: "+"; position: absolute; right: 4px; top: 14px; font-size: 1.3rem; color: var(--color-teal); font-weight: 400;
}
.faq-item.open .faq-question::after { content: "−"; }
.faq-answer { max-height: 0; overflow: hidden; transition: max-height .25s ease; color: var(--color-text-mute); font-size: .93rem; }
.faq-item.open .faq-answer { max-height: 600px; }
.faq-answer-inner { padding: 0 0 16px; }
.faq-group-title { font-size: 1.15rem; margin: 34px 0 6px; color: var(--color-ink); }
.faq-group-title:first-child { margin-top: 0; }

/* ---------- Callout / 学习使用说明 ---------- */
.callout {
  background: var(--color-warn-bg); border: 1px solid var(--color-warn-border); color: var(--color-warn-text);
  border-radius: var(--radius-md); padding: 16px 20px; font-size: .9rem; margin: 20px 0;
}
.callout strong { color: var(--color-warn-text); }
.callout-title { font-weight: 800; margin-bottom: 4px; display: block; }

/* ---------- Tabs (demo widgets) ---------- */
.tabs-bar { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; }
.tab-btn {
  padding: 8px 16px; border-radius: 999px; border: 1px solid var(--color-border); background: var(--color-surface);
  cursor: pointer; font-size: .88rem; font-weight: 600; color: var(--color-ink-soft); font-family: inherit;
}
.tab-btn.active { background: var(--color-ink); color: #fff; border-color: var(--color-ink); }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

/* ---------- Demo shell ---------- */
.demo-shell {
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-lg);
  padding: 26px; box-shadow: var(--shadow-md);
}
.demo-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; align-items: start; }
.demo-note { font-size: .82rem; color: var(--color-text-mute); margin-top: 14px; }

/* ---------- Table ---------- */
.table-wrap { overflow-x: auto; margin: 20px 0; border: 1px solid var(--color-border); border-radius: var(--radius-md); }
table { border-collapse: collapse; width: 100%; min-width: 560px; font-size: .9rem; }
th, td { padding: 12px 16px; text-align: left; border-bottom: 1px solid var(--color-border); }
th { background: var(--color-bg-alt); color: var(--color-ink); font-weight: 700; }
tr:last-child td { border-bottom: none; }

/* ---------- Breadcrumb ---------- */
.breadcrumb { font-size: .85rem; color: var(--color-text-mute); padding: 16px 0 0; }
.breadcrumb a { color: var(--color-text-mute); }
.breadcrumb .sep { margin: 0 6px; }

/* ---------- Internal link list ---------- */
.link-fan { display: grid; gap: 10px; }
.link-fan a {
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
  background: var(--color-surface); border: 1px solid var(--color-border); border-radius: var(--radius-md);
  padding: 14px 18px; color: var(--color-ink); font-weight: 600; font-size: .93rem;
}
.link-fan a:hover { border-color: var(--color-teal); color: var(--color-teal); text-decoration: none; }
.link-fan a .arrow { color: var(--color-teal); }

/* ---------- App feature grid ---------- */
.app-feature { display: flex; gap: 14px; align-items: flex-start; padding: 16px 0; border-bottom: 1px solid var(--color-border); }
.app-feature:last-child { border-bottom: none; }
.app-feature-icon { width: 40px; height: 40px; flex: none; }
.app-feature h4 { font-size: .98rem; margin-bottom: .3em; }
.app-feature p { font-size: .88rem; color: var(--color-text-mute); margin-bottom: 0; }

/* ---------- Download badges ---------- */
.download-row { display: flex; flex-wrap: wrap; gap: 14px; margin: 20px 0; }
.download-badge {
  display: flex; align-items: center; gap: 10px; padding: 12px 18px; border-radius: var(--radius-md);
  border: 1px dashed var(--color-border); background: var(--color-surface); color: var(--color-text-mute);
  font-size: .88rem; font-weight: 600;
}
.download-badge img { width: 26px; height: 26px; }
.download-badge .status { font-size: .76rem; color: var(--color-gold); font-weight: 700; }

/* ---------- Footer ---------- */
.site-footer { background: var(--color-ink); color: #C9D2E6; margin-top: 40px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 30px; padding: 48px 0 24px; }
.footer-brand { display: flex; align-items: center; gap: 10px; font-weight: 800; color: #fff; font-size: 1.1rem; margin-bottom: 10px; }
.footer-brand img { width: 30px; height: 30px; }
.footer-desc { color: #9FAAC6; font-size: .87rem; max-width: 42ch; }
.footer-col h4 { color: #fff; font-size: .92rem; margin-bottom: 12px; }
.footer-col ul { list-style: none; padding: 0; margin: 0; }
.footer-col li { margin-bottom: 8px; }
.footer-col a { color: #AEB8D1; font-size: .87rem; }
.footer-col a:hover { color: #fff; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.12); padding: 18px 0 28px; font-size: .8rem; color: #8B96B4;
  display: flex; flex-wrap: wrap; gap: 10px; justify-content: space-between;
}
.footer-legal-slot { color: #6C7893; }

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed; right: 22px; bottom: 22px; width: 44px; height: 44px; border-radius: 50%;
  background: var(--color-ink); color: #fff; border: none; cursor: pointer; font-size: 1.1rem;
  box-shadow: var(--shadow-lg); display: none; align-items: center; justify-content: center; z-index: 90;
}
.back-to-top.show { display: flex; }

/* ---------- Utility ---------- */
.mt-0 { margin-top: 0; }
.text-mute { color: var(--color-text-mute); }
.center { text-align: center; }
.small { font-size: .85rem; }
.stack-lg > * + * { margin-top: 20px; }
.pill-row { display: flex; flex-wrap: wrap; gap: 10px; margin: 16px 0; }
.divider { border: none; border-top: 1px solid var(--color-border); margin: 30px 0; }

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 1024px) {
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .arch-diagram { grid-template-columns: 1fr; }
  .priority-board { grid-template-columns: 1fr; }
}

@media (max-width: 860px) {
  .hero-inner { grid-template-columns: 1fr; }
  .demo-grid { grid-template-columns: 1fr; }
  .tree-level { grid-template-columns: 1fr; }
  .tree-level-label { padding-top: 0; }
  .funnel-row { grid-template-columns: 90px 1fr; }
  .funnel-count { grid-column: 1 / -1; }
}

@media (max-width: 1180px) {
  .nav-menu {
    position: fixed; top: 66px; left: 0; right: 0; bottom: 0; background: var(--color-bg);
    flex-direction: column; align-items: stretch; padding: 14px; gap: 2px; overflow-y: auto;
    transform: translateX(100%); transition: transform .25s ease; border-top: 1px solid var(--color-border);
  }
  .nav-menu.open { transform: translateX(0); }
  .nav-menu a { padding: 14px 16px; font-size: 1rem; white-space: normal; }
  .nav-toggle { display: block; }
}

@media (max-width: 768px) {
  .hero-title { font-size: 1.55rem; }
  .section-title { font-size: 1.3rem; }
  .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; padding-bottom: 10px; }
  .article-block { padding: 22px 18px; }
  .error-chain-step { grid-template-columns: 1fr; }
}

@media (max-width: 430px) {
  .container { padding: 0 16px; }
  .hero { padding: 40px 0 32px; }
  .section { padding: 40px 0; }
  .funnel-row { grid-template-columns: 1fr; }
}