/* ===== 超脑 AI 协作系统教程 v2 · 设计系统 ===== */
:root{
  --ink:#1d1d1f; --ink2:#515154; --ink3:#86868b; --line:#e3e3e6;
  --gray:#f5f5f7; --gray2:#fafafptext; --blue:#06c; --maxw:1080px; --textw:720px;
  --acc:#06c;            /* 每页可覆盖：道紫/法蓝/术橙/器绿 */
  --acc-soft:#eaf2ff;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;background:#fff;color:var(--ink);
  font-family:-apple-system,BlinkMacSystemFont,"SF Pro Display","SF Pro Text","PingFang SC","Helvetica Neue","Microsoft YaHei",sans-serif;
  -webkit-font-smoothing:antialiased;line-height:1.55;font-size:17px;letter-spacing:.004em}
img{max-width:100%;display:block}
a{color:var(--acc);text-decoration:none}
.container{max-width:var(--maxw);margin:0 auto;padding:0 28px}
.narrow{max-width:var(--textw);margin-left:auto;margin-right:auto}

/* progress */
#progress{position:fixed;top:0;left:0;height:3px;width:0;z-index:200;background:var(--acc);transition:width .1s}

/* nav */
.nav{position:sticky;top:0;z-index:100;height:52px;display:flex;align-items:center;gap:16px;
  padding:0 22px;background:rgba(255,255,255,.72);backdrop-filter:saturate(180%) blur(20px);
  -webkit-backdrop-filter:saturate(180%) blur(20px);border-bottom:1px solid rgba(0,0,0,.07)}
.nav .brand{font-weight:600;font-size:15.5px;white-space:nowrap;color:var(--ink)}
.nav .brand a{color:var(--ink)}
.nav .sp{flex:1}
.nav .links{display:flex;gap:2px;overflow-x:auto;scrollbar-width:none}
.nav .links::-webkit-scrollbar{display:none}
.nav .links a{color:var(--ink2);font-size:13.5px;padding:6px 11px;border-radius:980px;white-space:nowrap}
.nav .links a:hover,.nav .links a.on{color:var(--ink);background:rgba(0,0,0,.05)}

/* reveal */
.reveal{opacity:0;transform:translateY(22px);transition:opacity .7s cubic-bezier(.2,.7,.2,1),transform .7s cubic-bezier(.2,.7,.2,1)}
.reveal.in{opacity:1;transform:none}

/* ===== block: section wrapper ===== */
.block{padding:64px 0}
.block.tight{padding:40px 0}
.block.bg{background:var(--gray)}
.eyebrow{font-size:14px;font-weight:600;letter-spacing:.06em;color:var(--acc);text-align:center;margin-bottom:14px}

/* ===== hero ===== */
.hero{text-align:center;padding:118px 24px 64px}
.hero .kicker{color:var(--acc);font-weight:600;font-size:20px;margin-bottom:14px}
.hero h1{font-size:clamp(40px,7vw,78px);line-height:1.06;font-weight:700;letter-spacing:-.022em;margin:0 0 22px}
.hero h1 .g{background:linear-gradient(120deg,#ff7a45,#06c);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero .lead{font-size:clamp(19px,2.2vw,26px);color:var(--ink2);max-width:720px;margin:0 auto;line-height:1.42;font-weight:400}
.hero .meta{color:var(--ink3);font-size:14.5px;margin-top:24px}

/* chapter page header */
.chead{text-align:center;padding:96px 24px 8px}
.chead .cnum{font-size:17px;font-weight:600;color:var(--ink3);letter-spacing:.1em}
.tag{display:inline-block;font-size:12.5px;font-weight:600;color:#fff;background:var(--acc);padding:3px 13px;border-radius:980px;letter-spacing:.06em;margin:14px 0 16px}
.chead h1{font-size:clamp(32px,5.2vw,58px);line-height:1.08;font-weight:700;letter-spacing:-.02em;margin:0 auto;max-width:14em}
.chead .sub{color:var(--ink2);font-size:clamp(18px,2vw,22px);margin:18px auto 0;max-width:30em;line-height:1.45}

/* ===== block: statement (big idea) ===== */
.statement{text-align:center;max-width:18em;margin:0 auto;font-size:clamp(28px,4.4vw,50px);
  line-height:1.16;font-weight:700;letter-spacing:-.018em}
.statement .hl{color:var(--acc)}
.statement.sm{font-size:clamp(24px,3.4vw,38px);max-width:22em}
.substatement{text-align:center;max-width:34em;margin:22px auto 0;font-size:clamp(18px,2vw,21px);color:var(--ink2);line-height:1.5}

/* ===== block: stat (big number) ===== */
.stat{text-align:center}
.stat .num{font-size:clamp(72px,14vw,150px);font-weight:700;line-height:1;letter-spacing:-.03em;
  background:linear-gradient(120deg,var(--acc),#9a6cff);-webkit-background-clip:text;background-clip:text;color:transparent}
.stat .cap{font-size:clamp(18px,2.2vw,24px);color:var(--ink2);margin-top:16px;max-width:24em;margin-left:auto;margin-right:auto;line-height:1.45}

/* ===== block: cards grid ===== */
.cards{display:grid;gap:20px}
.cards.c2{grid-template-columns:repeat(2,1fr)}
.cards.c3{grid-template-columns:repeat(3,1fr)}
.card{background:#fff;border:1px solid var(--line);border-radius:22px;padding:30px 28px;transition:transform .18s,box-shadow .18s}
.bg .card{background:#fff}
.card:hover{transform:translateY(-3px);box-shadow:0 16px 40px rgba(0,0,0,.08)}
.card .ic{font-size:30px;margin-bottom:14px;line-height:1}
.card h3{font-size:21px;font-weight:650;margin:0 0 8px;letter-spacing:-.01em}
.card p{font-size:15.5px;color:var(--ink2);margin:0;line-height:1.55}
.card .lead-num{font-size:14px;font-weight:700;color:var(--acc);margin-bottom:10px}

/* ===== block: split comparison (vs) ===== */
.split{display:grid;grid-template-columns:1fr auto 1fr;gap:0;align-items:stretch;max-width:880px;margin:0 auto}
.split .side{border:1px solid var(--line);border-radius:22px;padding:30px 28px;background:#fff}
.split .side.bad{background:#fff}
.split .side .lbl{font-size:13px;font-weight:700;letter-spacing:.04em;margin-bottom:14px;display:inline-block;padding:3px 12px;border-radius:980px}
.split .side.bad .lbl{color:#86868b;background:#f0f0f2}
.split .side.good .lbl{color:#fff;background:var(--acc)}
.split .side h4{font-size:19px;margin:0 0 12px;font-weight:650}
.split .side ul{margin:0;padding-left:1.1em}
.split .side li{margin:8px 0;font-size:15.5px;color:var(--ink2)}
.split .vs{display:flex;align-items:center;justify-content:center;width:64px;font-weight:700;color:var(--ink3);font-size:15px}

/* ===== block: steps (flow) ===== */
.steps{display:grid;gap:14px;counter-reset:s}
.step{display:flex;gap:18px;align-items:flex-start;background:#fff;border:1px solid var(--line);
  border-radius:18px;padding:20px 22px;cursor:pointer;transition:border-color .15s,box-shadow .15s}
.step:hover{border-color:var(--acc);box-shadow:0 8px 24px rgba(0,0,0,.05)}
.step .n{flex:none;width:42px;height:42px;border-radius:50%;background:var(--acc-soft);color:var(--acc);
  font-weight:700;font-size:19px;display:grid;place-items:center}
.step .body h4{margin:0;font-size:18.5px;font-weight:650}
.step .body .d{margin:6px 0 0;font-size:15.5px;color:var(--ink2);line-height:1.55}
.step .body .more{margin:10px 0 0;font-size:14.5px;color:var(--ink2);line-height:1.6;
  max-height:0;overflow:hidden;opacity:0;transition:max-height .35s ease,opacity .3s}
.step.open .more{max-height:300px;opacity:1;margin-top:12px}
.step .chev{margin-left:auto;color:var(--ink3);transition:transform .25s;flex:none;align-self:center}
.step.open .chev{transform:rotate(180deg)}

/* ===== block: hub diagram (svg-ish, css) ===== */
.hub-wrap{max-width:920px;margin:0 auto}
.hub{display:grid;grid-template-columns:1fr 1fr 1fr;gap:16px;align-items:center}
.hub .core{grid-column:2;grid-row:1/3;background:linear-gradient(135deg,var(--acc),#9a6cff);color:#fff;
  border-radius:24px;padding:28px;text-align:center;box-shadow:0 18px 50px rgba(0,102,204,.2)}
.hub .core .t{font-size:22px;font-weight:700}
.hub .core .s{font-size:14px;opacity:.9;margin-top:6px}
.spoke{background:#fff;border:1px solid var(--line);border-radius:16px;padding:16px 18px;transition:transform .15s,box-shadow .15s}
.spoke:hover{transform:translateY(-2px);box-shadow:0 10px 26px rgba(0,0,0,.07)}
.spoke .k{font-size:12.5px;font-weight:700;color:var(--acc);margin-bottom:5px}
.spoke .t{font-size:16px;font-weight:600}
.spoke .d{font-size:13.5px;color:var(--ink3);margin-top:4px;line-height:1.5}

/* ===== block: stack (layers) ===== */
.stack{max-width:760px;margin:0 auto;display:grid;gap:10px}
.layer{display:flex;align-items:center;gap:18px;border-radius:16px;padding:18px 24px;color:#fff;position:relative}
.layer .ll{font-size:13px;font-weight:700;opacity:.85;width:84px;flex:none}
.layer .lt{font-size:18px;font-weight:650}
.layer .ld{margin-left:auto;font-size:14px;opacity:.92;text-align:right;max-width:48%}

/* ===== block: iconlist ===== */
.iconlist{max-width:var(--textw);margin:0 auto;display:grid;gap:16px}
.iconlist .it{display:flex;gap:16px;align-items:flex-start}
.iconlist .it .ic{font-size:24px;flex:none;line-height:1.2}
.iconlist .it .tx{font-size:17px;color:var(--ink);line-height:1.55}
.iconlist .it .tx b{font-weight:650}

/* ===== block: metaphor (image + 1 line) ===== */
.metaphor{text-align:center}
.metaphor .pic{max-width:var(--maxw);margin:0 auto;border-radius:26px;overflow:hidden;box-shadow:0 24px 64px rgba(0,0,0,.12)}
.metaphor .pic img{width:100%;aspect-ratio:16/9;object-fit:cover;background:var(--gray)}
.metaphor .cap{font-size:clamp(20px,2.6vw,30px);font-weight:650;margin:30px auto 0;max-width:20em;line-height:1.3;letter-spacing:-.01em}
.metaphor .cap .hl{color:var(--acc)}
.metaphor .sub{font-size:17px;color:var(--ink2);margin:14px auto 0;max-width:30em;line-height:1.5}

/* ===== block: fig (贴切小图 · 中等尺寸点缀) ===== */
.fig{max-width:var(--textw);margin:0 auto;text-align:center}
.fig img{width:100%;aspect-ratio:16/9;object-fit:cover;border-radius:22px;box-shadow:0 18px 50px rgba(0,0,0,.1);background:var(--gray)}
.fig .cap{font-size:14.5px;color:var(--ink3);margin-top:14px;line-height:1.5}

/* ===== block: pullquote ===== */
.pull{max-width:18em;margin:0 auto;text-align:center;font-size:clamp(24px,3.2vw,38px);
  font-weight:600;line-height:1.28;letter-spacing:-.012em}
.pull .by{display:block;font-size:15px;font-weight:500;color:var(--ink3);margin-top:18px;letter-spacing:0}

/* ===== block: deep (accordion) ===== */
.deep{max-width:var(--textw);margin:26px auto 0}
.deep>summary{list-style:none;cursor:pointer;display:inline-flex;align-items:center;gap:8px;
  font-size:15px;font-weight:600;color:var(--acc);padding:10px 18px;border:1px solid var(--line);
  border-radius:980px;background:#fff;transition:background .15s}
.deep>summary::-webkit-details-marker{display:none}
.deep>summary:hover{background:var(--acc-soft)}
.deep>summary .pm{transition:transform .2s}
.deep[open]>summary .pm{transform:rotate(45deg)}
.deep .dc{padding:22px 4px 0;font-size:16.5px;color:var(--ink2);line-height:1.7}
.deep .dc p{margin:14px 0}
.deep .dc strong{color:var(--ink);font-weight:600}
.deep .dc blockquote{margin:16px 0;padding-left:18px;border-left:3px solid var(--line);color:var(--ink);font-style:normal}

/* ===== chapter map (index) · 干净白卡 ===== */
.chmap{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}
.chcard{display:block;border:1px solid var(--line);border-radius:20px;background:#fff;
  padding:24px 24px 22px;transition:transform .18s,box-shadow .18s,border-color .18s;color:var(--ink)}
.chcard:hover{transform:translateY(-3px);box-shadow:0 18px 40px rgba(0,0,0,.07);border-color:#d6d6db}
.chcard .top{display:flex;align-items:center;justify-content:space-between;margin-bottom:15px}
.chcard .no{font-size:38px;font-weight:800;color:#e7e7ec;letter-spacing:-.02em;line-height:1}
.chcard .lyr{font-size:12px;font-weight:600;padding:3px 11px;border-radius:980px}
.lyr.shu{color:#b95a26;background:#f7efe8}
.lyr.dao{color:#6a51c9;background:#efebfa}
.lyr.fa{color:#0a62c9;background:#e9f1fd}
.lyr.qi{color:#2e8650;background:#ecf5ef}
.chcard h3{font-size:18px;font-weight:650;margin:0 0 7px;letter-spacing:-.01em}
.chcard p{font-size:13.5px;color:var(--ink2);margin:0;line-height:1.5}

/* ===== 道法术器 · 克制细条 ===== */
.lvls{max-width:760px;margin:0 auto;display:grid;gap:10px}
.lvl{display:flex;align-items:center;gap:16px;border:1px solid var(--line);border-radius:14px;padding:15px 20px;background:#fff;transition:box-shadow .15s}
.lvl:hover{box-shadow:0 8px 22px rgba(0,0,0,.05)}
.lvl .b{width:34px;height:34px;border-radius:10px;display:grid;place-items:center;color:#fff;font-weight:700;font-size:16px;flex:none}
.lvl .nm{font-size:17px;font-weight:650;color:var(--ink)}
.lvl .ds{margin-left:auto;font-size:13.5px;color:var(--ink3);text-align:right}
@media(max-width:600px){.lvl .ds{display:none}}

/* ===== prevnext ===== */
.prevnext{display:flex;justify-content:space-between;gap:16px;max-width:var(--maxw);margin:0 auto;padding:60px 28px 20px}
.prevnext a{flex:1;border:1px solid var(--line);border-radius:18px;padding:20px 24px;background:#fff;transition:border-color .15s,box-shadow .15s}
.prevnext a:hover{border-color:var(--acc);box-shadow:0 10px 28px rgba(0,0,0,.06)}
.prevnext .dir{font-size:13px;color:var(--ink3);margin-bottom:6px}
.prevnext .ttl{font-size:18px;font-weight:650;color:var(--ink)}
.prevnext .next{text-align:right}

footer{background:var(--gray);color:var(--ink3);font-size:13px;padding:40px 24px;text-align:center;line-height:1.7;border-top:1px solid var(--line)}
footer a{color:var(--ink2)}

@media(max-width:820px){
  .cards.c3,.chmap{grid-template-columns:1fr 1fr}
  .hub{grid-template-columns:1fr}
  .hub .core{grid-column:1;grid-row:auto;order:-1}
  .layer .ld{display:none}
}
@media(max-width:600px){
  .block{padding:48px 0}
  .cards.c2,.cards.c3,.chmap{grid-template-columns:1fr}
  .split{grid-template-columns:1fr}
  .split .vs{width:auto;padding:8px 0}
  .prevnext{flex-direction:column}
}