:root{
  --bg:#0b0d12;--panel:#12151c;--panel2:#171b24;--line:#252b37;
  --text:#e7eaf0;--muted:#9aa3b2;--brand:#5b8cff;--brand2:#7c5bff;
  --ok:#3ecf8e;--warn:#ffb454;--radius:14px;--maxw:1080px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font:15px/1.7 -apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",Segoe UI,sans-serif;
  background:var(--bg);color:var(--text);-webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 20px}

/* nav */
.nav{position:sticky;top:0;z-index:20;background:rgba(11,13,18,.82);
  backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav .wrap{display:flex;align-items:center;height:60px;gap:18px}
.logo{display:flex;align-items:center;gap:10px;font-weight:700;font-size:17px}
.logo .dot{width:22px;height:22px;border-radius:7px;
  background:linear-gradient(135deg,var(--brand),var(--brand2))}
.nav nav{margin-left:auto;display:flex;gap:22px;color:var(--muted);font-size:14px}
.nav nav a:hover{color:var(--text)}
.logo-sub{font-size:11px;font-weight:600;color:var(--brand);border:1px solid rgba(91,140,255,.4);
  border-radius:6px;padding:2px 7px;margin-left:4px}
.menu-btn{display:none;margin-left:auto;background:none;border:1px solid var(--line);color:var(--text);
  border-radius:8px;width:38px;height:34px;font-size:18px;cursor:pointer}

/* doc layout */
.layout{display:flex;max-width:1180px;margin:0 auto;align-items:flex-start}
.sidebar{width:282px;flex:none;position:sticky;top:60px;align-self:flex-start;
  height:calc(100vh - 60px);overflow-y:auto;border-right:1px solid var(--line);padding:22px 14px 40px}
.content{flex:1;min-width:0}
.content .article{margin:0;max-width:780px}
.sb-home{display:block;font-size:13px;color:var(--muted);padding:8px 12px;margin-bottom:6px;
  border-radius:8px;border:1px solid var(--line)}
.sb-home:hover{color:var(--brand);border-color:var(--brand)}
.sb-dir{display:block;font-weight:600;font-size:14px;padding:9px 12px;margin-bottom:12px;
  border-radius:8px;background:var(--panel)}
.sb-dir:hover{color:var(--brand)}
.sb-dir.active{color:var(--brand);background:rgba(91,140,255,.08)}
.sb-group{margin-bottom:4px}
.sb-head{width:100%;display:flex;align-items:center;justify-content:space-between;gap:8px;
  background:none;border:none;color:var(--text);font-size:13.5px;font-weight:600;
  padding:9px 12px;cursor:pointer;text-align:left;border-radius:8px}
.sb-head:hover{background:var(--panel)}
.sb-head .chev{color:var(--muted);transition:transform .18s;font-size:12px}
.sb-group.open .sb-head .chev{transform:rotate(180deg)}
.sb-list{display:none;padding:2px 0 8px}
.sb-group.open .sb-list{display:block}
.sb-item{display:flex;align-items:center;gap:10px;padding:7px 12px 7px 14px;font-size:13px;
  color:var(--muted);border-radius:7px;border-left:2px solid transparent;line-height:1.4}
.sb-item:hover{color:var(--text);background:var(--panel)}
.sb-item.active{color:var(--brand);background:rgba(91,140,255,.08);border-left-color:var(--brand);font-weight:600}
.sb-n{flex:none;width:20px;height:20px;border-radius:5px;background:var(--panel2);color:var(--muted);
  font-size:11px;font-weight:600;display:flex;align-items:center;justify-content:center}
.sb-item.active .sb-n{background:var(--brand);color:#fff}

@media(max-width:860px){
  .sidebar{position:fixed;top:60px;left:0;z-index:30;background:var(--bg);width:280px;
    transform:translateX(-105%);transition:transform .22s;box-shadow:0 0 40px rgba(0,0,0,.5)}
  .sidebar.open{transform:translateX(0)}
  .menu-btn{display:block}
  .content .article{padding:28px 18px 70px}
}

/* hero */
.hero{padding:72px 0 48px;text-align:center;position:relative;overflow:hidden}
.hero::before{content:"";position:absolute;inset:-40% 0 auto 0;height:420px;
  background:radial-gradient(60% 100% at 50% 0,rgba(91,140,255,.18),transparent 70%);pointer-events:none}
.hero h1{font-size:40px;line-height:1.2;letter-spacing:-.5px}
.hero h1 .g{background:linear-gradient(135deg,var(--brand),var(--brand2));
  -webkit-background-clip:text;background-clip:text;color:transparent}
.hero p{color:var(--muted);max-width:620px;margin:16px auto 0;font-size:16px}
.tag{display:inline-block;font-size:12px;color:var(--brand);
  border:1px solid rgba(91,140,255,.4);border-radius:999px;padding:4px 12px;margin-bottom:18px}
.cta{display:inline-flex;gap:10px;margin-top:28px}
.btn{display:inline-flex;align-items:center;gap:8px;padding:11px 20px;border-radius:10px;
  font-weight:600;font-size:14px;border:1px solid var(--line);transition:.15s}
.btn.primary{background:linear-gradient(135deg,var(--brand),var(--brand2));border:none;color:#fff}
.btn.primary:hover{filter:brightness(1.08)}
.btn.ghost:hover{border-color:var(--brand);color:var(--brand)}

/* section */
.sec{padding:44px 0}
.sec h2{font-size:24px;letter-spacing:-.3px}
.sec .sub{color:var(--muted);margin-top:6px;font-size:14px}
.sec-head{display:flex;align-items:flex-end;justify-content:space-between;gap:16px;margin-bottom:24px}

/* course grid */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:18px}
.card{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);
  padding:22px;transition:.18s;display:flex;flex-direction:column}
.card:hover{border-color:var(--brand);transform:translateY(-3px)}
.card .badge{font-size:11px;color:var(--brand);font-weight:600;letter-spacing:.5px;text-transform:uppercase}
.card h3{font-size:18px;margin:10px 0 8px}
.card p{color:var(--muted);font-size:13.5px;flex:1}
.card .meta{display:flex;gap:14px;margin-top:16px;color:var(--muted);font-size:12.5px;
  border-top:1px solid var(--line);padding-top:14px}
.card .meta b{color:var(--text);font-weight:600}
.soon{opacity:.55}
.soon:hover{transform:none;border-color:var(--line)}

/* lesson list */
.lessons{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}
.lrow{display:flex;align-items:center;gap:16px;padding:16px 20px;border-bottom:1px solid var(--line);transition:.15s}
.lrow:last-child{border-bottom:none}
.lrow:hover{background:var(--panel2)}
.lnum{width:30px;height:30px;flex:none;border-radius:8px;background:var(--panel2);
  display:flex;align-items:center;justify-content:center;font-size:13px;color:var(--muted);font-weight:600}
.ltitle{flex:1}
.ltitle b{font-weight:600}
.ltitle small{display:block;color:var(--muted);font-size:12.5px;margin-top:2px}
.ldur{color:var(--muted);font-size:12.5px;flex:none}

/* article (lesson page) */
.article{max-width:760px;margin:0 auto;padding:40px 20px 80px}
.crumb{color:var(--muted);font-size:13px;margin-bottom:18px}
.crumb a:hover{color:var(--brand)}
.article h1{font-size:30px;line-height:1.25;margin-bottom:8px}
.article .lead{color:var(--muted);font-size:16px;margin:14px 0 30px}
.article h2{font-size:21px;margin:38px 0 12px;padding-top:8px}
.article h3{font-size:17px;margin:26px 0 10px}
.article p{margin:12px 0}
.article ul,.article ol{margin:12px 0 12px 22px}
.article li{margin:6px 0}
.article code{background:var(--panel2);border:1px solid var(--line);border-radius:5px;
  padding:1px 6px;font-size:13px;font-family:"SF Mono",Menlo,Consolas,monospace}
.article pre{background:var(--panel);border:1px solid var(--line);border-radius:10px;
  padding:16px;overflow:auto;margin:16px 0}
.article pre code{background:none;border:none;padding:0;font-size:13px;line-height:1.6}
.callout{background:var(--panel);border:1px solid var(--line);border-left:3px solid var(--brand);
  border-radius:10px;padding:16px 18px;margin:20px 0}
.callout.warn{border-left-color:var(--warn)}
.callout.ok{border-left-color:var(--ok)}
.callout b{display:block;margin-bottom:4px}
/* scenario box */
.scenario{background:linear-gradient(135deg,rgba(91,140,255,.08),rgba(124,91,255,.06));
  border:1px solid var(--line);border-radius:10px;padding:14px 18px;margin:18px 0;font-size:14.5px}
.scenario b{color:var(--brand)}

/* steps */
.steps{counter-reset:step;margin:18px 0;position:relative;padding-left:6px}
.step{position:relative;padding:0 0 20px 40px;border-left:2px solid var(--line);margin-left:13px}
.step:last-child{border-left-color:transparent;padding-bottom:0}
.step::before{counter-increment:step;content:counter(step);position:absolute;left:-15px;top:-2px;
  width:28px;height:28px;border-radius:50%;background:var(--panel2);border:1px solid var(--line);
  color:var(--brand);font-weight:700;font-size:13px;display:flex;align-items:center;justify-content:center}
.step .st{font-weight:600;margin-bottom:8px;display:block}

/* copyable prompt card */
.prompt{position:relative;background:#0e1118;border:1px solid var(--line);border-radius:10px;
  margin:10px 0;overflow:hidden}
.prompt .phead{display:flex;align-items:center;justify-content:space-between;
  padding:7px 12px;background:var(--panel2);border-bottom:1px solid var(--line);font-size:12px;color:var(--muted)}
.prompt .phead .lbl{display:flex;align-items:center;gap:6px}
.prompt .phead .lbl::before{content:"💬"}
.copy{cursor:pointer;border:1px solid var(--line);background:var(--panel);color:var(--muted);
  border-radius:6px;padding:3px 10px;font-size:11.5px;transition:.15s}
.copy:hover{border-color:var(--brand);color:var(--brand)}
.copy.done{color:var(--ok);border-color:var(--ok)}
.prompt pre{margin:0;border:none;border-radius:0;background:none;padding:13px 14px;white-space:pre-wrap}
.prompt pre code{font-family:"PingFang SC","Microsoft YaHei",-apple-system,sans-serif;font-size:13.5px;line-height:1.65}

/* compare table */
.ctable{width:100%;border-collapse:collapse;margin:18px 0;font-size:13.5px;
  border:1px solid var(--line);border-radius:10px;overflow:hidden}
.ctable th,.ctable td{text-align:left;padding:11px 14px;border-bottom:1px solid var(--line)}
.ctable th{background:var(--panel2);color:var(--text);font-weight:600}
.ctable tr:last-child td{border-bottom:none}
.ctable td:first-child{color:var(--brand);font-weight:600;white-space:nowrap}

.navlinks{display:flex;justify-content:space-between;margin-top:48px;gap:14px}
.navlinks a{flex:1;padding:16px;border:1px solid var(--line);border-radius:10px;color:var(--muted);transition:.15s}
.navlinks a:hover{border-color:var(--brand);color:var(--text)}
.navlinks small{display:block;font-size:12px;margin-bottom:4px}

/* footer */
footer{border-top:1px solid var(--line);padding:30px 0;color:var(--muted);font-size:13px;margin-top:40px}
footer .wrap{display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px}

@media(max-width:600px){.hero h1{font-size:30px}.nav nav{display:none}}