/* ======================= course app ======================= */
body.course{background:var(--paper)}
.screen{display:none}
.screen.on{display:block}

/* ---------- auth ---------- */
.auth{min-height:100vh;background:var(--pink);place-items:center;padding:40px var(--gut);overflow:hidden}
.auth .in{width:100%;max-width:1180px;display:grid;grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);gap:56px;align-items:center}
#auth.on{display:grid}
.auth .mega{font-size:clamp(40px,5.3vw,82px)}
.auth .mega span:last-child{color:var(--paper);-webkit-text-stroke:2px var(--ink)}
.auth .lead{max-width:44ch;font-weight:600;margin:22px 0 0}
.term{font-size:14px}
.term .body{padding:24px}
.term .line{font-weight:700;margin:0 0 16px}
.term .line b{color:#c2185b}
.term .hint{font-size:12.5px;color:var(--mute);margin:14px 0 0;font-weight:500}
.term .row2{display:flex;flex-wrap:wrap;gap:14px;align-items:center;margin-top:6px}
.linkbtn{background:none;border:0;padding:0;font-weight:700;text-decoration:underline;cursor:pointer;font-size:13px}
.linkbtn:disabled{opacity:.45;cursor:default;text-decoration:none}
.otp{display:grid;grid-template-columns:repeat(6,1fr);gap:8px;margin:4px 0 8px}
.otp input{height:64px;border:2px solid var(--ink);text-align:center;font-family:var(--display);font-size:30px;background:var(--paper);width:100%;border-radius:0;padding:0}
.otp input:focus{outline:none;background:var(--pink);box-shadow:4px 4px 0 var(--ink)}
.stat{display:inline-block;margin-top:14px;font-size:12.5px;font-weight:700}
.stat.err{color:#c2185b}
@media (max-width:900px){.auth .in{grid-template-columns:1fr;gap:28px}}

/* ---------- app shell ---------- */
.top{position:sticky;top:0;z-index:40;background:var(--ink);color:#fff;height:52px;display:flex;align-items:stretch;border-bottom:2px solid var(--ink)}
.top .brand{display:flex;align-items:center;gap:10px;padding:0 18px;font-weight:800;font-size:14px;text-decoration:none;color:#fff;border-right:2px solid #2a2a2a}
.top .brand .dots{display:flex;gap:5px}.top .brand .dots i{width:8px;height:8px;border-radius:50%;background:var(--pink);display:block}
.top .menu{display:none;background:none;border:0;color:#fff;padding:0 16px;font-weight:800;cursor:pointer;border-right:2px solid #2a2a2a}
.top .meter{flex:1;display:flex;align-items:center;gap:14px;padding:0 18px;min-width:0}
.top .meter .track{flex:1;height:14px;border:2px solid #fff;position:relative;max-width:420px;background-image:radial-gradient(#555 1px,transparent 1.3px);background-size:5px 5px}
.top .meter .fillb{position:absolute;inset:0 auto 0 0;background:var(--pink);transition:width .5s}
.top .meter span{font-size:12.5px;font-weight:700;white-space:nowrap}
.top .who{display:flex;align-items:center;gap:14px;padding:0 16px;font-size:12.5px;border-left:2px solid #2a2a2a;min-width:0}
.top .who span{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:220px;color:#bdbac0}
.top .who button{background:var(--paper);color:var(--ink);border:0;font-weight:800;padding:6px 10px;cursor:pointer;font-size:12px}
.shell{display:grid;grid-template-columns:320px minmax(0,1fr);min-height:calc(100vh - 52px)}

/* sidebar tree */
.side{border-right:2px solid var(--ink);background:var(--panel);position:sticky;top:52px;height:calc(100vh - 52px);overflow-y:auto}
.side .bar{position:sticky;top:0;z-index:2}
.tree{padding:8px 0 40px}
.tree h4{margin:18px 18px 8px;font-size:12px;font-weight:800;display:flex;justify-content:space-between}
.tree h4 small{font-weight:500;color:var(--mute)}
.tree a{display:grid;grid-template-columns:34px 1fr 22px;align-items:center;gap:8px;padding:9px 18px;text-decoration:none;font-size:13.5px;font-weight:600;border-left:4px solid transparent}
.tree a:hover{background:#fff}
.tree a .n{font-weight:800;font-size:12px;color:var(--mute)}
.tree a .ok{font-size:12px;font-weight:800;color:#c2185b}
.tree a.cur{background:var(--ink);color:#fff;border-left-color:var(--hot)}
.tree a.cur .n{color:var(--pink)}
.tree a.cur .ok{color:var(--pink)}
.tree a.lock{opacity:.5;pointer-events:none}

/* chapter */
.main{min-width:0}
.hero-ch{background:var(--pink);border-bottom:2px solid var(--ink);padding:56px clamp(20px,5vw,72px) 44px;overflow:hidden}
.hero-ch .kick{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:22px}
.hero-ch h1{font-family:var(--display);font-weight:400;text-transform:uppercase;font-size:clamp(44px,7vw,112px);line-height:.86;letter-spacing:-.025em;margin:0;max-width:14ch}
.hero-ch .sum{max-width:62ch;font-size:16.5px;font-weight:600;margin:22px 0 0}
.hero-ch .build{margin-top:26px;display:inline-flex;border:2px solid var(--ink);background:var(--paper);font-size:13px;font-weight:700}
.hero-ch .build span{padding:8px 12px}
.hero-ch .build span:first-child{background:var(--ink);color:#fff}

.doc{padding:48px clamp(20px,5vw,72px) 40px;display:grid;grid-template-columns:minmax(0,760px) minmax(0,220px);gap:56px;justify-content:start}
.toc{position:sticky;top:84px;align-self:start;font-size:12.5px}
.toc b{display:block;font-size:12px;margin-bottom:10px}
.toc a{display:block;text-decoration:none;padding:6px 0 6px 12px;border-left:2px solid #d6d3d9;color:var(--mute);font-weight:600;line-height:1.4}
.toc a.on{border-left-color:var(--hot);color:var(--ink)}
@media (max-width:1240px){.doc{grid-template-columns:minmax(0,760px)}.toc{display:none}}

/* prose */
.prose{font-size:15.5px;line-height:1.78}
.prose>*:first-child{margin-top:0}
.prose p{margin:0 0 18px}
.prose h2{font-family:var(--display);font-weight:400;text-transform:uppercase;font-size:clamp(28px,3.4vw,42px);line-height:.95;letter-spacing:-.01em;margin:64px 0 22px;padding-top:22px;border-top:3px solid var(--ink);scroll-margin-top:80px}
.prose h3{font-size:17px;font-weight:800;margin:36px 0 12px;scroll-margin-top:80px}
.prose h3:before{content:"> ";color:#c2185b}
.prose ul,.prose ol{margin:0 0 20px;padding:0;list-style:none}
.prose ul li{position:relative;padding-left:26px;margin:0 0 8px}
.prose ul li:before{content:"-";position:absolute;left:6px;font-weight:800;color:#c2185b}
.prose ol{counter-reset:o}
.prose ol li{position:relative;padding-left:40px;margin:0 0 10px;counter-increment:o}
.prose ol li:before{content:counter(o);position:absolute;left:0;top:3px;width:26px;height:22px;background:var(--ink);color:#fff;font-size:12px;font-weight:800;display:grid;place-items:center;line-height:1}
.prose strong{font-weight:800}
.prose a{text-decoration-thickness:2px;text-decoration-color:var(--hot)}
.prose :not(pre)>code{background:#fde3ea;border:1px solid #f3b6c7;padding:1px 5px;font-size:.92em;font-weight:600;word-break:break-word}
.prose blockquote{margin:28px 0;padding:0 0 0 22px;border-left:6px solid var(--hot);font-family:var(--display);font-size:clamp(22px,2.6vw,30px);line-height:1.1;text-transform:uppercase}
.prose blockquote p{margin:0}
.prose hr{border:0;height:14px;margin:48px 0;background-image:radial-gradient(var(--ink) 1.2px,transparent 1.6px);background-size:10px 10px;opacity:.5}
.prose table{width:100%;border-collapse:collapse;font-size:13.5px;line-height:1.5}
.prose .tw{border:2px solid var(--ink);margin:26px 0;overflow-x:auto;box-shadow:6px 6px 0 var(--ink);background:var(--paper)}
.prose th,.prose td{text-align:left;padding:11px 14px;border-bottom:1.5px solid #d6d3d9;vertical-align:top}
.prose th{background:var(--ink);color:#fff;font-size:12px;font-weight:700;border-bottom:0}
.prose tr:last-child td{border-bottom:0}
.prose td:first-child{font-weight:800}

/* code windows */
.cw{margin:26px 0;border:2px solid var(--ink);background:#0d0c0f;color:#eceaf0;box-shadow:6px 6px 0 var(--hot)}
.cw .bar{background:var(--ink);border-bottom:2px solid #2a2830}
.cw .bar .lang{font-size:11.5px;color:var(--pink);font-weight:700}
.cw .bar .cp{background:var(--pink);color:var(--ink);border:0;font:inherit;font-weight:800;font-size:12px;padding:3px 10px;cursor:pointer}
.cw .bar .cp.ok{background:#fff}
.cw pre{margin:0;padding:18px 20px;overflow-x:auto;font-size:13.5px;line-height:1.7;tab-size:4}
.cw pre code{font-family:var(--mono)}
.cw.term{background:var(--paper);color:var(--ink);box-shadow:6px 6px 0 var(--ink)}
.cw.term pre{font-weight:600}
.cw.term .gp{color:#c2185b;user-select:none}
/* pygments tokens */
.cw .k,.cw .kn,.cw .kd,.cw .kc,.cw .ow{color:#ff7aa2;font-weight:700}
.cw .s,.cw .s1,.cw .s2,.cw .sd,.cw .sa,.cw .se,.cw .si{color:#f9c6d4}
.cw .c,.cw .c1,.cw .cm,.cw .ch{color:#8a8594;font-style:italic}
.cw .mi,.cw .mf,.cw .m{color:#ffd166}
.cw .nf,.cw .nc{color:#fff;font-weight:800}
.cw .nb,.cw .bp{color:#a6e3ff}
.cw .nd{color:#ff7aa2}
.cw .o,.cw .p{color:#cfcbd6}
.cw .nt{color:#ff7aa2}
.cw .kt{color:#a6e3ff}
.cw.term .nb,.cw.term .nv,.cw.term .o{color:inherit}

/* callouts */
.co{margin:28px 0;border:2px solid var(--ink);background:var(--paper)}
.co .body{padding:16px 20px;font-size:14.5px;line-height:1.7}
.co .body>*:last-child{margin-bottom:0}
.co.note .bar{background:var(--ink)}
.co.note{background:var(--panel)}
.co.warn .bar{background:var(--hot)}
.co.warn{background:#fff0f4}
.co.try{box-shadow:6px 6px 0 var(--ink)}
.co.try .bar{background:var(--ink)}
.co.try .body{background:var(--pink)}
.co.me .bar{background:#c2185b}
.co.me .body{font-weight:500}
.rule-box{margin:34px 0;background:var(--ink);color:#fff;padding:26px 28px;font-family:var(--display);text-transform:uppercase;font-size:clamp(22px,2.8vw,32px);line-height:1.05;position:relative;overflow:hidden}
.rule-box em{font-style:normal;color:var(--pink)}
.rule-box small{display:block;font-family:var(--mono);text-transform:none;font-size:13px;color:#bdbac0;margin-top:12px;font-weight:500;line-height:1.5}

/* figures */
.fig{margin:32px 0;border:2px solid var(--ink);background:var(--paper)}
.fig .body{padding:22px}
.fig figcaption{border-top:2px solid var(--ink);padding:10px 16px;font-size:12.5px;font-weight:600;background:var(--panel)}
.lanes{display:grid;grid-template-columns:repeat(3,1fr);gap:0;border:2px solid var(--ink)}
.lanes>div{padding:16px;border-right:2px solid var(--ink);min-width:0}
.lanes>div:last-child{border-right:0}
.lanes .h{font-family:var(--display);text-transform:uppercase;font-size:20px;line-height:1;margin-bottom:10px}
.lanes .mid{background:var(--pink)}
.lanes ul{list-style:none;margin:0;padding:0;font-size:12.5px;font-weight:600}
.lanes li{padding:5px 0;border-bottom:1px dashed #b9b6be}
.lanes li:last-child{border-bottom:0}
@media (max-width:700px){.lanes{grid-template-columns:1fr}.lanes>div{border-right:0;border-bottom:2px solid var(--ink)}.lanes>div:last-child{border-bottom:0}}
.trace{font-size:13px;display:grid;gap:6px}
.trace .t{display:grid;grid-template-columns:110px 1fr 90px;gap:12px;align-items:center;padding:8px 10px;border:2px solid var(--ink)}
.trace .t b{font-weight:800}
.trace .t .who{font-size:11.5px;font-weight:800;padding:2px 6px;text-align:center}
.trace .t.gen .who{background:var(--paper);border:1.5px solid var(--ink)}
.trace .t.dec{background:var(--pink)}
.trace .t.dec .who{background:var(--ink);color:#fff}
.trace .t.exe .who{background:var(--panel);border:1.5px solid var(--ink)}
@media (max-width:620px){.trace .t{grid-template-columns:1fr}}
.bars2{display:grid;gap:12px;font-size:13px;font-weight:700}
.bars2 .r{display:grid;grid-template-columns:150px 1fr 70px;gap:12px;align-items:center}
.bars2 .tr{height:20px;border:2px solid var(--ink);position:relative;background:var(--paper)}
.bars2 .tr i{position:absolute;inset:0 auto 0 0;background:var(--ink)}
.bars2 .r.hot .tr i{background:var(--hot)}
@media (max-width:620px){.bars2 .r{grid-template-columns:1fr 60px}.bars2 .r .tr{grid-column:1/-1;grid-row:2}}
.cmp{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.cmp>div{border:2px solid var(--ink);padding:16px;font-size:13px}
.cmp>div:last-child{background:var(--pink)}
.cmp .h{font-weight:800;font-size:12px;margin-bottom:8px}
.cmp pre{margin:0;white-space:pre-wrap;font-size:12.5px;line-height:1.6}
@media (max-width:700px){.cmp{grid-template-columns:1fr}}

/* checkpoint */
.quiz{margin:30px 0;border:2px solid var(--ink)}
.quiz summary{list-style:none;cursor:pointer;padding:14px 18px;display:grid;grid-template-columns:auto 1fr auto;gap:14px;align-items:center;font-weight:700;font-size:14.5px}
.quiz summary::-webkit-details-marker{display:none}
.quiz summary .q{background:var(--ink);color:#fff;font-size:11.5px;padding:3px 8px}
.quiz summary .r{font-size:12px;border:2px solid var(--ink);padding:2px 8px}
.quiz[open] summary{border-bottom:2px solid var(--ink);background:var(--pink)}
.quiz[open] summary .r{background:var(--ink);color:#fff}
.quiz .a{padding:16px 18px;font-size:14px}
.quiz .a p:last-child{margin-bottom:0}

/* end of chapter */
.built{margin:56px 0 0;border:2px solid var(--ink);display:grid;grid-template-columns:auto 1fr}
.built .l{background:var(--ink);color:#fff;font-family:var(--display);font-size:22px;padding:18px;writing-mode:vertical-rl;transform:rotate(180deg);text-transform:uppercase;letter-spacing:.02em}
.built .r{padding:18px 20px}
.built .r ul{margin:0}
.pager{display:grid;grid-template-columns:1fr auto 1fr;gap:16px;align-items:stretch;padding:0 clamp(20px,5vw,72px) 80px;max-width:1100px}
.pager a{border:2px solid var(--ink);text-decoration:none;padding:14px 18px;display:block;background:var(--paper);min-width:0}
.pager a:hover{background:var(--pink)}
.pager a small{display:block;font-size:11.5px;font-weight:700;color:var(--mute)}
.pager a b{display:block;font-size:15px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.pager .nx{text-align:right;box-shadow:6px 6px 0 var(--ink)}
.pager .done{align-self:center;height:56px}
.pager .done.is{background:var(--hot)}
.pager .ghost{visibility:hidden}
@media (max-width:760px){.pager{grid-template-columns:1fr}.pager .nx{text-align:left}}

.empty{padding:120px clamp(20px,5vw,72px);max-width:760px}
.empty .mega{font-size:clamp(40px,6vw,84px)}

@media (max-width:960px){
  .shell{grid-template-columns:1fr}
  .side{position:fixed;top:52px;left:0;bottom:0;width:min(340px,88vw);z-index:45;transform:translateX(-105%);transition:transform .2s;height:auto;box-shadow:8px 0 0 var(--ink)}
  body.menu-open .side{transform:none}
  .top .menu{display:block}
  .top .who span{display:none}
  .top .meter .track{display:none}
}
@media (max-width:600px){
  .top .brand{display:none}
  .top .meter{padding:0 12px}
  .top .who{padding:0 10px}
  .top .who button{white-space:nowrap}
  .hero-ch{padding:36px 20px 32px}
}