/* ===========================================================
   골다공증 연수강좌 — clinical reference site
   =========================================================== */
:root{
  --bg:#f4f6f9; --bg-2:#eef1f5; --surface:#ffffff; --surface-2:#f8fafc;
  --ink:#11181c; --ink-2:#3c4a52; --ink-3:#6b7a85; --line:#e3e8ee; --line-2:#eef2f6;
  --brand:#0e7c86; --brand-ink:#0a5860;
  --hip:#0e7c86; --hip-a:#13a3b0;
  --knee:#2563a8; --knee-a:#3b82d6;
  --infection:#b45309; --infection-a:#d97706;
  --fracture:#7c3aed; --fracture-a:#9061f0;
  --shadow:0 1px 2px rgba(16,24,40,.04),0 6px 20px -8px rgba(16,24,40,.12);
  --shadow-lg:0 8px 40px -12px rgba(16,24,40,.28);
  --radius:16px; --radius-sm:10px;
  --maxw:1480px; --sidebar:288px; --toc:230px;
  --sans:"Pretendard Variable",Pretendard,-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Apple SD Gothic Neo","Noto Sans KR",sans-serif;
  --mono:"SF Mono",ui-monospace,"Cascadia Code","JetBrains Mono",Menlo,Consolas,monospace;
}
[data-theme="dark"]{
  --bg:#0d1014; --bg-2:#0a0d11; --surface:#161b22; --surface-2:#1b212a;
  --ink:#e8edf2; --ink-2:#aebac4; --ink-3:#7c8a96; --line:#262d36; --line-2:#1e242c;
  --brand:#2bb7c4; --brand-ink:#7fe0e9;
  --hip:#1ab0bd; --hip-a:#2bc5d2; --knee:#5b9be8; --knee-a:#74aef0;
  --infection:#e08a2b; --infection-a:#f0a23e; --fracture:#a784f5; --fracture-a:#bb9ff8;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 8px 26px -10px rgba(0,0,0,.6);
  --shadow-lg:0 14px 50px -14px rgba(0,0,0,.7);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;font-family:var(--sans);background:var(--bg);color:var(--ink);
  line-height:1.7;font-size:16px;-webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;letter-spacing:-.003em;
}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
::selection{background:color-mix(in srgb,var(--brand) 28%,transparent)}

/* scrollbars */
*::-webkit-scrollbar{width:11px;height:11px}
*::-webkit-scrollbar-thumb{background:var(--line);border-radius:20px;border:3px solid transparent;background-clip:content-box}
*::-webkit-scrollbar-thumb:hover{background:var(--ink-3)}

/* ---------- Top bar ---------- */
.topbar{
  position:sticky;top:0;z-index:60;height:60px;display:flex;align-items:center;gap:16px;
  padding:0 20px;background:color-mix(in srgb,var(--surface) 86%,transparent);
  backdrop-filter:saturate(1.4) blur(14px);border-bottom:1px solid var(--line);
}
.brand{display:flex;align-items:center;gap:11px;font-weight:800;letter-spacing:-.02em;cursor:pointer;color:var(--ink)}
.brand .logo{width:30px;height:30px;border-radius:9px;display:grid;place-items:center;
  background:linear-gradient(135deg,var(--brand),var(--knee-a));color:#fff;box-shadow:var(--shadow)}
.brand .logo svg{width:18px;height:18px}
.brand b{font-size:16.5px}
.brand small{display:block;font-size:10.5px;color:var(--ink-3);font-weight:600;letter-spacing:.02em;margin-top:-2px}
.topbar .spacer{flex:1}
.menu-btn{display:none;background:none;border:1px solid var(--line);border-radius:9px;width:38px;height:38px;color:var(--ink);cursor:pointer}

/* search */
.search{position:relative;width:min(360px,42vw)}
.search input{
  width:100%;height:40px;border:1px solid var(--line);background:var(--surface-2);
  border-radius:11px;padding:0 14px 0 38px;color:var(--ink);font-family:inherit;font-size:14px;outline:none;transition:.15s;
}
.search input:focus{border-color:var(--brand);box-shadow:0 0 0 3px color-mix(in srgb,var(--brand) 16%,transparent);background:var(--surface)}
.search svg{position:absolute;left:12px;top:11px;width:17px;height:17px;color:var(--ink-3)}
.search kbd{position:absolute;right:9px;top:9px;font-size:11px;font-family:var(--mono);color:var(--ink-3);
  border:1px solid var(--line);border-radius:6px;padding:2px 6px;background:var(--surface)}
.icon-btn{background:none;border:1px solid var(--line);border-radius:9px;width:40px;height:40px;color:var(--ink-2);cursor:pointer;
  display:grid;place-items:center;transition:.15s}
.icon-btn:hover{color:var(--brand);border-color:var(--brand)}
.icon-btn svg{width:18px;height:18px}

/* ---------- Layout ---------- */
.shell{max-width:var(--maxw);margin:0 auto;display:grid;grid-template-columns:var(--sidebar) minmax(0,1fr);gap:0}
.sidebar{
  position:sticky;top:60px;align-self:start;height:calc(100vh - 60px);overflow-y:auto;
  border-right:1px solid var(--line);padding:18px 14px 60px;
}
.main{min-width:0;padding:0 0 80px}

/* sidebar nav */
.nav-sec{margin-bottom:6px}
.nav-home{display:flex;align-items:center;gap:10px;padding:9px 12px;border-radius:10px;color:var(--ink-2);font-weight:700;font-size:14px;cursor:pointer}
.nav-home:hover{background:var(--surface-2);text-decoration:none}
.nav-home.active{background:color-mix(in srgb,var(--brand) 12%,transparent);color:var(--brand)}
.nav-group{margin-top:10px}
.nav-gh{display:flex;align-items:center;gap:9px;width:100%;border:none;background:none;cursor:pointer;
  padding:9px 12px;border-radius:10px;color:var(--ink);font-family:inherit;font-weight:750;font-size:13.5px;text-align:left}
.nav-gh:hover{background:var(--surface-2)}
.nav-gh .dot{width:9px;height:9px;border-radius:3px;flex:none}
.nav-gh .cnt{margin-left:auto;font-size:11px;color:var(--ink-3);font-weight:700;background:var(--surface-2);border-radius:20px;padding:1px 8px;border:1px solid var(--line)}
.nav-gh .chev{width:15px;height:15px;color:var(--ink-3);transition:transform .2s;flex:none}
.nav-group.collapsed .chev{transform:rotate(-90deg)}
.nav-items{margin:2px 0 4px 17px;border-left:1.5px solid var(--line);padding-left:5px;overflow:hidden}
.nav-group.collapsed .nav-items{display:none}
.nav-item{display:block;padding:6px 10px;border-radius:8px;font-size:12.7px;color:var(--ink-2);cursor:pointer;
  white-space:nowrap;overflow:hidden;text-overflow:ellipsis;line-height:1.45}
.nav-item:hover{background:var(--surface-2);color:var(--ink);text-decoration:none}
.nav-item.active{background:color-mix(in srgb,var(--accent,var(--brand)) 14%,transparent);color:var(--accent,var(--brand));font-weight:650}
.nav-item .num{font-family:var(--mono);font-size:11px;color:var(--ink-3);margin-right:6px}

/* ---------- Content column ---------- */
.wrap{max-width:1180px;margin:0 auto;padding:0 32px}
.view{animation:fade .35s ease}
@keyframes fade{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}

/* hero */
.hero{position:relative;overflow:hidden;border-bottom:1px solid var(--line);
  background:
   radial-gradient(900px 360px at 12% -10%,color-mix(in srgb,var(--hip) 20%,transparent),transparent 60%),
   radial-gradient(820px 360px at 92% 0%,color-mix(in srgb,var(--knee) 18%,transparent),transparent 62%),
   radial-gradient(700px 320px at 60% 120%,color-mix(in srgb,var(--fracture) 14%,transparent),transparent 60%);
}
.hero-in{max-width:1180px;margin:0 auto;padding:56px 32px 44px}
.kicker{display:inline-flex;align-items:center;gap:8px;font-size:12px;font-weight:750;letter-spacing:.12em;
  color:var(--brand-ink);text-transform:uppercase;background:color-mix(in srgb,var(--brand) 12%,transparent);
  border:1px solid color-mix(in srgb,var(--brand) 24%,transparent);padding:5px 12px;border-radius:30px}
.hero h1{font-size:clamp(30px,4.6vw,50px);line-height:1.08;letter-spacing:-.035em;margin:18px 0 8px;font-weight:850}
.hero .lead{font-size:clamp(15px,1.7vw,18.5px);color:var(--ink-2);max-width:62ch;margin:0 0 22px}
.hero-meta{display:flex;flex-wrap:wrap;gap:9px;align-items:center}
.chip{display:inline-flex;align-items:center;gap:7px;font-size:13px;font-weight:650;color:var(--ink-2);
  background:var(--surface);border:1px solid var(--line);border-radius:30px;padding:6px 13px;box-shadow:var(--shadow)}
.chip b{color:var(--ink);font-variant-numeric:tabular-nums}
.chip svg{width:15px;height:15px;color:var(--brand)}
.src-links{display:flex;flex-wrap:wrap;gap:10px;margin-top:18px}
.src-links a{display:inline-flex;align-items:center;gap:8px;font-size:13px;font-weight:650;color:var(--ink-2);
  border:1px solid var(--line);background:var(--surface);border-radius:10px;padding:8px 13px;box-shadow:var(--shadow)}
.src-links a:hover{color:var(--brand);border-color:var(--brand);text-decoration:none;transform:translateY(-1px)}
.src-links svg{width:16px;height:16px}

/* section heading */
.sec-h{display:flex;align-items:baseline;gap:12px;margin:42px 0 18px}
.sec-h h2{font-size:21px;font-weight:800;letter-spacing:-.02em;margin:0;display:inline-flex;align-items:center;gap:8px}
.sec-h h2 svg{width:20px;height:20px;color:var(--c);flex:none;transform:translateY(1px)}
.sec-h .sub{font-size:13px;color:var(--ink-3);font-weight:600}

/* topic cards grid */
.t-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}
.t-card{position:relative;display:flex;flex-direction:column;background:var(--surface);border:1px solid var(--line);
  border-radius:var(--radius);padding:22px 22px 20px;box-shadow:var(--shadow);cursor:pointer;overflow:hidden;transition:.2s}
.t-card::before{content:"";position:absolute;inset:0 0 auto 0;height:4px;background:linear-gradient(90deg,var(--c),var(--ca))}
.t-card:hover{transform:translateY(-3px);box-shadow:var(--shadow-lg);border-color:color-mix(in srgb,var(--c) 40%,var(--line))}
.t-card .top{display:flex;align-items:center;gap:14px;margin-bottom:13px}
.t-ic{width:46px;height:46px;border-radius:13px;flex:none;display:grid;place-items:center;color:#fff;
  background:linear-gradient(135deg,var(--c),var(--ca));box-shadow:0 6px 16px -6px var(--c)}
.t-ic svg{width:25px;height:25px}
.t-card h3{margin:0;font-size:18.5px;font-weight:800;letter-spacing:-.02em}
.t-card .en{font-size:12px;color:var(--ink-3);font-weight:600;letter-spacing:.01em}
.t-card .blurb{font-size:13.6px;color:var(--ink-2);line-height:1.62;margin:0 0 16px;flex:1}
.t-card .foot{display:flex;align-items:center;gap:8px;font-size:12.5px;color:var(--ink-3);font-weight:650}
.t-pill{display:inline-flex;align-items:center;gap:6px;background:color-mix(in srgb,var(--c) 12%,transparent);
  color:var(--c);border-radius:20px;padding:3px 10px;font-weight:750}
.t-pill svg{width:14px;height:14px}
.t-pill-supp{background:color-mix(in srgb,var(--c) 10%,transparent);color:var(--c)}
.t-card .go{margin-left:auto;color:var(--c);display:inline-flex;align-items:center;gap:5px;font-weight:750}
.t-card .go svg{width:15px;height:15px;transition:transform .2s}
.t-card:hover .go svg{transform:translateX(3px)}

/* topic view header */
.topic-head{position:relative;padding:38px 0 24px;border-bottom:1px solid var(--line);margin-bottom:8px}
.topic-head .tag{font-family:var(--mono);font-size:12px;font-weight:700;letter-spacing:.1em;color:var(--c);
  background:color-mix(in srgb,var(--c) 12%,transparent);padding:4px 10px;border-radius:7px;display:inline-block}
.topic-head h1{font-size:clamp(26px,3.4vw,36px);margin:14px 0 6px;letter-spacing:-.03em;font-weight:850;
  display:flex;align-items:center;gap:14px}
.topic-head h1 .hi{width:40px;height:40px;border-radius:12px;display:grid;place-items:center;color:#fff;
  background:linear-gradient(135deg,var(--c),var(--ca))}
.topic-head h1 .hi svg{width:23px;height:23px}
.topic-head .en{color:var(--ink-3);font-size:14px;font-weight:600}
.topic-head .blurb{margin:14px 0 0;color:var(--ink-2);font-size:15px;max-width:75ch}

/* lecture list */
.lec-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(330px,1fr));gap:14px;margin-top:22px}
.lec-card{display:flex;gap:14px;background:var(--surface);border:1px solid var(--line);border-radius:14px;
  padding:16px 17px;cursor:pointer;box-shadow:var(--shadow);transition:.16s;align-items:flex-start}
.lec-card:hover{transform:translateY(-2px);border-color:color-mix(in srgb,var(--c) 38%,var(--line));box-shadow:var(--shadow-lg)}
.lec-num{font-family:var(--mono);font-size:13px;font-weight:700;color:#fff;background:linear-gradient(135deg,var(--c),var(--ca));
  width:30px;height:30px;border-radius:9px;display:grid;place-items:center;flex:none}
.lec-card h4{margin:0 0 4px;font-size:14.8px;font-weight:740;line-height:1.4;letter-spacing:-.01em;color:var(--ink)}
.lec-meta{display:flex;flex-wrap:wrap;gap:8px;align-items:center;font-size:12px;color:var(--ink-3)}
.lec-spk{display:inline-flex;align-items:center;gap:5px;font-weight:650;color:var(--ink-2)}
.lec-spk::before{content:"";width:5px;height:5px;border-radius:50%;background:var(--c)}
.lec-toc{color:var(--ink-3)}

/* 심화 보충 정리 (accordion) */
.supp-lead{font-size:13.8px;color:var(--ink-2);line-height:1.62;margin:-6px 0 16px}
.supp-lead strong{color:var(--ink);font-weight:720}
.supp-list{display:flex;flex-direction:column;gap:11px}
.supp{background:var(--surface);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);
  overflow:hidden;transition:border-color .15s,box-shadow .15s;scroll-margin-top:72px}
.supp[open]{border-color:color-mix(in srgb,var(--c) 45%,var(--line));box-shadow:var(--shadow-lg)}
.supp>summary{list-style:none;cursor:pointer;display:flex;align-items:center;gap:13px;padding:15px 18px;user-select:none}
.supp>summary::-webkit-details-marker{display:none}
.supp>summary:hover{background:color-mix(in srgb,var(--c) 5%,transparent)}
.supp-n{width:34px;height:34px;border-radius:10px;flex:none;display:grid;place-items:center;color:#fff;
  background:linear-gradient(135deg,var(--c),var(--ca))}
.supp-n svg{width:18px;height:18px}
.supp-tt{min-width:0;display:flex;flex-direction:column;gap:3px;flex:1}
.supp-tt b{font-size:15px;color:var(--ink);font-weight:760;line-height:1.35;letter-spacing:-.01em}
.supp-tag{font-size:11.5px;color:var(--ink-3);font-weight:650}
.supp-tag::before{content:"#";opacity:.55;margin-right:1px}
.supp-chev{margin-left:auto;color:var(--ink-3);flex:none;display:grid;place-items:center;transition:transform .2s}
.supp-chev svg{width:19px;height:19px}
.supp[open] .supp-chev{transform:rotate(180deg);color:var(--c)}
.supp-body{border-top:1px solid var(--line);padding:6px 20px 18px;animation:suppIn .22s ease}
.supp-body>*:first-child{margin-top:.7em}
.supp-body>*:last-child{margin-bottom:0}
@keyframes suppIn{from{opacity:0;transform:translateY(-4px)}to{opacity:1;transform:none}}
.sr-sub{font-size:12.5px;font-weight:750;color:var(--ink-3);letter-spacing:.01em;margin:20px 0 -4px;text-transform:none}
.sr-sub:first-child{margin-top:8px}

/* ---------- Lecture detail ---------- */
.lecview{display:grid;grid-template-columns:minmax(0,1fr) var(--toc);gap:40px;align-items:start;padding-top:26px}
.breadcrumb{display:flex;align-items:center;gap:7px;font-size:12.5px;color:var(--ink-3);font-weight:600;margin-bottom:14px;flex-wrap:wrap}
.breadcrumb a{color:var(--ink-3)}.breadcrumb a:hover{color:var(--brand)}
.breadcrumb svg{width:13px;height:13px;opacity:.6}
.lec-hd{border-bottom:1px solid var(--line);padding-bottom:20px;margin-bottom:8px}
.lec-hd .tagrow{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:11px}
.lec-hd .ttag{font-family:var(--mono);font-size:11.5px;font-weight:700;letter-spacing:.08em;color:#fff;
  background:linear-gradient(135deg,var(--c),var(--ca));padding:3px 9px;border-radius:6px}
.lec-hd .spk{font-size:13px;color:var(--ink-2);font-weight:650;display:inline-flex;gap:6px;align-items:center}
.lec-hd .spk svg{width:14px;height:14px;color:var(--c)}
.lec-hd h1{font-size:clamp(23px,3vw,32px);line-height:1.18;letter-spacing:-.03em;margin:0;font-weight:850}

/* article content */
.article{font-size:15.3px;color:var(--ink)}
.article p{margin:.7em 0;color:var(--ink-2)}
.article strong{color:var(--ink);font-weight:720}
.article em{color:var(--ink-2)}
.article .c-h{scroll-margin-top:74px;letter-spacing:-.02em;font-weight:800;line-height:1.3;color:var(--ink)}
.article h3.c-h{font-size:21px;margin:1.5em 0 .5em;padding-bottom:.3em;border-bottom:2px solid var(--line)}
.article h4.c-h{font-size:18px;margin:1.4em 0 .45em}
.article h5.c-h{font-size:15.6px;margin:1.25em 0 .4em;color:var(--ink)}
.article h6.c-h{font-size:14px;margin:1.1em 0 .35em;color:var(--ink-2)}
.article h4.c-h2{padding-left:13px;border-left:4px solid var(--c)}
.article ul,.article ol{margin:.55em 0;padding-left:1.35em}
.article li{margin:.32em 0;color:var(--ink-2)}
.article li::marker{color:var(--c)}
.article ul ul,.article ol ol,.article ul ol,.article ol ul{margin:.2em 0}
.article hr{border:none;border-top:1px solid var(--line);margin:1.4em 0}
.article a{font-weight:600;border-bottom:1px solid color-mix(in srgb,var(--brand) 30%,transparent)}

/* tables */
.tbl-wrap{overflow-x:auto;margin:1.1em 0;border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow)}
.article table{border-collapse:collapse;width:100%;font-size:13.8px;min-width:420px;background:var(--surface)}
.article thead th{background:linear-gradient(var(--surface-2),var(--surface-2));color:var(--ink);font-weight:750;
  text-align:left;padding:11px 14px;border-bottom:2px solid color-mix(in srgb,var(--c) 35%,var(--line));position:sticky;top:0}
.article tbody td{padding:10px 14px;border-bottom:1px solid var(--line-2);color:var(--ink-2);vertical-align:top}
.article tbody tr:nth-child(even){background:color-mix(in srgb,var(--surface-2) 55%,transparent)}
.article tbody tr:hover{background:color-mix(in srgb,var(--c) 6%,transparent)}
.article tbody tr:last-child td{border-bottom:none}
.article table strong{color:var(--ink)}

/* blockquote / callouts */
.article blockquote{margin:1em 0;padding:12px 16px;background:color-mix(in srgb,var(--c) 7%,var(--surface-2));
  border-left:4px solid var(--c);border-radius:0 10px 10px 0;color:var(--ink-2);font-size:14.4px}
.callout{margin:1.4em 0;border:1px solid color-mix(in srgb,var(--c) 30%,var(--line));border-radius:14px;
  background:color-mix(in srgb,var(--c) 7%,var(--surface));padding:6px 20px 16px;box-shadow:var(--shadow)}
.callout>.c-h{border:none!important;color:var(--c)!important;display:flex;align-items:center;gap:9px;padding-left:0!important;margin-top:.7em}
.callout>.c-h::before{content:"★";font-size:.9em}
.callout li::marker{color:var(--c)}

/* figures */
.fig{margin:1.3em 0;text-align:center}
.fig img{max-width:100%;border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow);cursor:zoom-in;transition:.18s}
.fig img:hover{box-shadow:var(--shadow-lg)}
.fig figcaption{font-size:12px;color:var(--ink-3);margin-top:7px;font-weight:600}
.cols{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin:1.2em 0}
.cols .col{min-width:0}.cols .fig{margin:.3em 0}

/* prev/next */
.pager{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-top:38px;padding-top:24px;border-top:1px solid var(--line)}
.pager a{display:flex;flex-direction:column;gap:3px;padding:14px 16px;border:1px solid var(--line);border-radius:13px;
  background:var(--surface);box-shadow:var(--shadow);transition:.15s}
.pager a:hover{border-color:var(--c);transform:translateY(-2px);text-decoration:none;box-shadow:var(--shadow-lg)}
.pager .lbl{font-size:11.5px;color:var(--ink-3);font-weight:650;display:flex;align-items:center;gap:5px}
.pager .nx{align-items:flex-end;text-align:right}
.pager .ti{font-size:14px;font-weight:720;color:var(--ink);line-height:1.35}
.pager svg{width:14px;height:14px}

/* TOC rail */
.toc{position:sticky;top:78px;align-self:start;max-height:calc(100vh - 96px);overflow-y:auto;font-size:12.8px}
.toc .lab{font-size:11px;font-weight:750;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);margin:0 0 10px;padding-left:12px}
.toc a{display:block;color:var(--ink-3);padding:4px 12px;border-left:2px solid var(--line);line-height:1.4;transition:.12s}
.toc a:hover{color:var(--ink);text-decoration:none}
.toc a.lv3{padding-left:24px;font-size:12.2px}
.toc a.active{color:var(--c);border-left-color:var(--c);font-weight:680;background:color-mix(in srgb,var(--c) 7%,transparent)}

/* search results */
.sr-head{padding:30px 0 6px}
.sr-head h1{font-size:24px;margin:0 0 4px;letter-spacing:-.02em}
.sr-head p{color:var(--ink-3);font-size:14px;margin:0}
.sr-list{margin-top:18px;display:flex;flex-direction:column;gap:11px}
.sr-item{background:var(--surface);border:1px solid var(--line);border-radius:13px;padding:15px 18px;cursor:pointer;box-shadow:var(--shadow);transition:.15s}
.sr-item:hover{border-color:var(--c);transform:translateX(3px);box-shadow:var(--shadow-lg)}
.sr-item .top{display:flex;align-items:center;gap:9px;margin-bottom:5px;flex-wrap:wrap}
.sr-item .tg{font-size:10.5px;font-family:var(--mono);font-weight:700;color:#fff;background:var(--c);padding:2px 7px;border-radius:5px}
.sr-item h4{margin:0;font-size:15px;font-weight:740}
.sr-item .snip{font-size:13px;color:var(--ink-2);line-height:1.6;max-height:3.2em;overflow:hidden}
.sr-item mark{background:color-mix(in srgb,var(--brand) 30%,transparent);color:var(--ink);border-radius:3px;padding:0 2px}
.empty{color:var(--ink-3);padding:40px 0;text-align:center;font-size:15px}

/* lightbox */
.lb{position:fixed;inset:0;z-index:100;background:rgba(8,10,14,.86);backdrop-filter:blur(6px);
  display:none;align-items:center;justify-content:center;padding:34px;cursor:zoom-out}
.lb.on{display:flex;animation:fade .2s}
.lb img{max-width:96vw;max-height:92vh;border-radius:10px;box-shadow:0 30px 90px -20px rgba(0,0,0,.8)}
.lb .x{position:absolute;top:18px;right:22px;color:#fff;background:rgba(255,255,255,.12);border:none;border-radius:10px;
  width:42px;height:42px;font-size:22px;cursor:pointer}

/* footer */
.foot{border-top:1px solid var(--line);margin-top:40px;padding:26px 0;color:var(--ink-3);font-size:12.5px}
.foot .wrap{display:flex;flex-wrap:wrap;gap:8px 18px;align-items:center;justify-content:space-between}
.foot a{color:var(--ink-2)}

/* mobile */
.backdrop{display:none}
@media(max-width:1180px){
  :root{--toc:0px}
  .lecview{grid-template-columns:minmax(0,1fr)}
  .toc{display:none}
}
@media(max-width:980px){
  .t-grid{grid-template-columns:1fr}
}
@media(max-width:820px){
  .shell{grid-template-columns:1fr}
  .menu-btn{display:grid;place-items:center}
  .search{width:auto;flex:1}
  .search kbd{display:none}
  .sidebar{position:fixed;top:60px;left:0;width:284px;background:var(--surface);z-index:55;
    transform:translateX(-103%);transition:transform .26s cubic-bezier(.4,0,.2,1);box-shadow:var(--shadow-lg)}
  .sidebar.open{transform:none}
  .backdrop.on{display:block;position:fixed;inset:60px 0 0;background:rgba(8,10,14,.4);z-index:54}
  .wrap,.hero-in{padding-left:20px;padding-right:20px}
  .brand small{display:none}
}
@media(max-width:560px){
  .lec-grid{grid-template-columns:1fr}
  .pager{grid-template-columns:1fr}
  .hero-in{padding-top:38px}
}

.t-ic-emoji{font-size:1.15em;line-height:1;display:inline-flex;align-items:center;justify-content:center}

/* handwritten lecture memo (leads each lecture) */
ul.memo{background:var(--surface-2,rgba(127,127,127,.06));border-left:3px solid var(--ca,#13a3b0);
  border-radius:8px;padding:.7em 1.1em .7em 1.6em;margin:.6em 0}
ul.memo li{margin:.25em 0;line-height:1.55}
ul.memo+ul.memo{margin-top:-.2em}