:root{
  --bg:#f7f6f1; --panel:#ffffff; --ink:#1d2a24; --muted:#5b6b62; --line:#dfe3da;
  --brand:#1f6b45; --brand-ink:#ffffff; --brand-soft:#e3f1e8; --accent:#c9831a;
  --code-bg:#14201a; --code-ink:#e8f1ea; --warn-bg:#fff4e0; --warn-line:#e0a233;
  --bad-bg:#fdebea; --bad-line:#d65a52; --ok-bg:#e6f4ea; --ok-line:#3d9a5a; --info-bg:#e8f1fb; --info-line:#4a86c8;
  --shadow:0 1px 2px rgba(0,0,0,.06),0 6px 20px rgba(0,0,0,.05);
  --side:300px; --radius:12px;
}
:root[data-theme="dark"]{
  --bg:#0f1713; --panel:#16211b; --ink:#e6eee8; --muted:#9bb0a3; --line:#27372e;
  --brand:#4fbf86; --brand-ink:#08140d; --brand-soft:#17352a; --accent:#e5a43d;
  --code-bg:#0a110d; --code-ink:#dff0e4; --warn-bg:#2d2412; --warn-line:#a87a24;
  --bad-bg:#321a19; --bad-line:#b5524b; --ok-bg:#15291c; --ok-line:#3a8a55; --info-bg:#14243a; --info-line:#4577b0;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 6px 20px rgba(0,0,0,.3);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --bg:#0f1713; --panel:#16211b; --ink:#e6eee8; --muted:#9bb0a3; --line:#27372e;
    --brand:#4fbf86; --brand-ink:#08140d; --brand-soft:#17352a; --accent:#e5a43d;
    --code-bg:#0a110d; --code-ink:#dff0e4; --warn-bg:#2d2412; --warn-line:#a87a24;
    --bad-bg:#321a19; --bad-line:#b5524b; --ok-bg:#15291c; --ok-line:#3a8a55; --info-bg:#14243a; --info-line:#4577b0;
  }
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:76px}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.7 system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;-webkit-text-size-adjust:100%}
a{color:var(--brand)}
a:hover{text-decoration-thickness:2px}
img{max-width:100%;height:auto}
code,pre,kbd{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace}

/* header */
.top{position:sticky;top:0;z-index:40;background:var(--panel);border-bottom:1px solid var(--line);display:flex;align-items:center;gap:10px;padding:10px 16px;min-height:60px}
.top .brand{display:flex;align-items:center;gap:10px;font-weight:700;text-decoration:none;color:var(--ink);white-space:nowrap}
.top .brand .logo{width:32px;height:32px;border-radius:9px;background:var(--brand);color:var(--brand-ink);display:grid;place-items:center;font-size:18px}
.top .brand small{display:block;font-weight:500;color:var(--muted);font-size:12px;line-height:1}
.top .spacer{flex:1}
.search{position:relative;flex:0 1 340px;min-width:120px}
.search input{width:100%;padding:9px 12px 9px 36px;border:1px solid var(--line);border-radius:999px;background:var(--bg);color:var(--ink);font:inherit;font-size:15px}
.search input:focus{outline:2px solid var(--brand);outline-offset:1px}
.search:before{content:"";position:absolute;left:13px;top:50%;width:11px;height:11px;margin-top:-8px;border:2px solid var(--muted);border-radius:50%}
.search:after{content:"";position:absolute;left:25px;top:50%;width:7px;height:2px;margin-top:5px;background:var(--muted);transform:rotate(45deg)}
.btn{appearance:none;border:1px solid var(--line);background:var(--panel);color:var(--ink);border-radius:10px;padding:8px 12px;font:inherit;font-size:15px;cursor:pointer;line-height:1.2}
.btn:hover{border-color:var(--brand)}
.btn.primary{background:var(--brand);border-color:var(--brand);color:var(--brand-ink);font-weight:600}
.btn.ghost{background:transparent}
.btn:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,button:focus-visible{outline:3px solid var(--accent);outline-offset:2px}
#menuBtn{display:none}
.meter{height:4px;background:var(--line);position:absolute;left:0;right:0;bottom:-1px}
.meter i{display:block;height:100%;width:0;background:var(--brand);transition:width .3s}

/* layout */
.shell{display:grid;grid-template-columns:var(--side) minmax(0,1fr);max-width:1280px;margin:0 auto}
nav.side{position:sticky;top:61px;align-self:start;height:calc(100vh - 61px);overflow:auto;padding:18px 14px 40px 18px;border-right:1px solid var(--line)}
nav.side h3{font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin:18px 8px 6px}
nav.side a{display:flex;gap:10px;align-items:flex-start;text-decoration:none;color:var(--ink);padding:8px 10px;border-radius:9px;font-size:15px;line-height:1.35}
nav.side a:hover{background:var(--brand-soft)}
nav.side a.on{background:var(--brand);color:var(--brand-ink);font-weight:600}
nav.side a .n{flex:0 0 24px;height:24px;border-radius:7px;background:var(--brand-soft);color:var(--brand);display:grid;place-items:center;font-size:12px;font-weight:700}
nav.side a.on .n{background:rgba(255,255,255,.25);color:var(--brand-ink)}
nav.side a .p{margin-left:auto;font-size:12px;color:var(--muted);white-space:nowrap}
nav.side a.on .p{color:var(--brand-ink)}
main{padding:28px clamp(16px,4vw,48px) 80px;min-width:0}
.page{max-width:780px;margin:0 auto}

/* content */
h1{font-size:clamp(28px,4.2vw,40px);line-height:1.18;margin:.2em 0 .3em;letter-spacing:-.01em}
h2{font-size:clamp(22px,3vw,28px);line-height:1.25;margin:2.1em 0 .5em;padding-top:.3em}
h3{font-size:19px;margin:1.6em 0 .4em}
p,li{max-width:70ch}
.lead{font-size:19px;color:var(--muted);margin:.2em 0 1em}
.kicker{color:var(--brand);font-weight:700;font-size:13px;letter-spacing:.08em;text-transform:uppercase}
.meta{display:flex;flex-wrap:wrap;gap:8px 14px;color:var(--muted);font-size:14px;margin:6px 0 18px}
.toc{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:14px 18px;margin:18px 0 8px}
.toc b{display:block;font-size:13px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin-bottom:4px}
.toc ol{margin:0;padding-left:20px}
.toc li{margin:2px 0}
table{border-collapse:collapse;width:100%;font-size:15px;margin:1em 0;display:block;overflow:auto}
th,td{border:1px solid var(--line);padding:8px 11px;text-align:left;vertical-align:top}
th{background:var(--brand-soft)}
td code,li code,p code,th code{background:var(--brand-soft);padding:1px 6px;border-radius:6px;font-size:.88em;word-break:break-word}
pre{position:relative;background:var(--code-bg);color:var(--code-ink);border-radius:10px;padding:14px 16px;overflow:auto;font-size:14px;line-height:1.55;margin:1em 0;tab-size:2}
pre code{background:none;padding:0;color:inherit;font-size:inherit}
pre .copy{position:absolute;top:8px;right:8px;background:rgba(255,255,255,.14);color:#fff;border:1px solid rgba(255,255,255,.3);border-radius:8px;padding:3px 10px;font-size:12px;cursor:pointer}
pre .copy:hover{background:rgba(255,255,255,.28)}
pre .lbl{position:absolute;top:8px;left:12px;font-size:11px;text-transform:uppercase;letter-spacing:.08em;color:#8fb7a0}
pre.has-lbl{padding-top:34px}
.note{border-left:5px solid var(--info-line);background:var(--info-bg);padding:12px 16px;border-radius:0 10px 10px 0;margin:1.2em 0}
.note.warn{border-color:var(--warn-line);background:var(--warn-bg)}
.note.bad{border-color:var(--bad-line);background:var(--bad-bg)}
.note.ok{border-color:var(--ok-line);background:var(--ok-bg)}
.note>:first-child{margin-top:0}.note>:last-child{margin-bottom:0}
.note .t{font-weight:700;display:block;margin-bottom:2px}
.tag{display:inline-block;font-size:12px;font-weight:700;padding:2px 9px;border-radius:999px;vertical-align:middle;margin-left:6px;border:1px solid}
.tag.ok{background:var(--ok-bg);border-color:var(--ok-line)}
.tag.try{background:var(--warn-bg);border-color:var(--warn-line)}
.tag.hyp{background:var(--info-bg);border-color:var(--info-line)}
figure{margin:1.4em 0;background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
figure img{display:block;width:100%;cursor:zoom-in;background:#fff}
figcaption{padding:10px 14px;font-size:14px;color:var(--muted);border-top:1px solid var(--line)}
.shot-note{font-size:13px;color:var(--muted)}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:14px;margin:1.2em 0}
.card{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:14px 16px;box-shadow:var(--shadow)}
.card b{display:block;margin-bottom:4px}
.card .ic{font-size:26px;display:block;margin-bottom:4px}
.flow{display:flex;flex-wrap:wrap;align-items:stretch;gap:8px;margin:1.2em 0}
.flow .st{flex:1 1 150px;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px;text-align:center;font-size:15px}
.flow .st b{display:block}
.flow .st small{color:var(--muted);display:block;margin-top:2px}
.flow .ar{align-self:center;color:var(--muted);font-size:22px}
.steps{counter-reset:s;list-style:none;padding:0;margin:1em 0}
.steps>li{counter-increment:s;position:relative;padding:0 0 14px 46px;margin:0;max-width:none}
.steps>li:before{content:counter(s);position:absolute;left:0;top:0;width:32px;height:32px;border-radius:50%;background:var(--brand);color:var(--brand-ink);display:grid;place-items:center;font-weight:700;font-size:15px}
.steps>li:not(:last-child):after{content:"";position:absolute;left:15px;top:36px;bottom:2px;width:2px;background:var(--line)}
ul.checklist{list-style:none;padding:0;margin:1em 0;background:var(--panel);border:1px solid var(--line);border-radius:var(--radius)}
ul.checklist li{padding:10px 14px;border-bottom:1px solid var(--line);max-width:none}
ul.checklist li:last-child{border-bottom:0}
ul.checklist label{display:flex;gap:12px;align-items:flex-start;cursor:pointer}
ul.checklist input{width:20px;height:20px;margin-top:4px;accent-color:var(--brand);flex:0 0 20px}
ul.checklist li.done span{color:var(--muted);text-decoration:line-through}
.cl-head{display:flex;justify-content:space-between;align-items:center;font-weight:700;margin-top:1.6em;gap:8px;flex-wrap:wrap}
.cl-head small{font-weight:500;color:var(--muted)}
details{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:2px 14px;margin:.8em 0}
details>summary{cursor:pointer;font-weight:600;padding:10px 0}
details[open]>summary{border-bottom:1px solid var(--line);margin-bottom:8px}
.kbd,kbd{background:var(--panel);border:1px solid var(--line);border-bottom-width:2px;border-radius:6px;padding:0 6px;font-size:.85em}

/* quiz */
.quiz{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:6px 18px 18px;margin-top:2.4em;box-shadow:var(--shadow)}
.quiz h2{margin-top:.8em}
.q{margin:1.2em 0}
.q p{font-weight:600;margin:.2em 0 .5em}
.q label{display:block;padding:8px 12px;border:1px solid var(--line);border-radius:9px;margin:6px 0;cursor:pointer}
.q label:hover{border-color:var(--brand)}
.q input{margin-right:8px;accent-color:var(--brand)}
.q.right label.sel{background:var(--ok-bg);border-color:var(--ok-line)}
.q.wrong label.sel{background:var(--bad-bg);border-color:var(--bad-line)}
.q.shown label.ans{background:var(--ok-bg);border-color:var(--ok-line)}
.q .why{display:none;font-size:15px;color:var(--muted);margin-top:6px}
.q.shown .why{display:block}
.score{font-weight:700;margin-left:10px}

/* pager */
.pager{display:flex;justify-content:space-between;gap:12px;margin-top:40px;flex-wrap:wrap}
.pager a{flex:1 1 220px;text-decoration:none;color:var(--ink);background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px 16px}
.pager a:hover{border-color:var(--brand)}
.pager a small{display:block;color:var(--muted);font-size:13px}
.pager a.next{text-align:right}

/* home */
.hero{background:linear-gradient(135deg,#17533a,#2b8a5a 60%,#c9831a);color:#fff;border-radius:18px;padding:clamp(22px,5vw,48px);margin-bottom:26px;box-shadow:var(--shadow)}
.hero h1{color:#fff;margin:.1em 0}
.hero p{color:#eef7f0;max-width:56ch}
.hero .btn{margin:6px 8px 0 0}
.hero .btn.primary{background:#fff;color:#17533a;border-color:#fff}
.hero .btn.ghost{color:#fff;border-color:rgba(255,255,255,.6)}
.chapgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:14px}
.chapgrid a{display:block;text-decoration:none;color:var(--ink);background:var(--panel);border:1px solid var(--line);border-radius:14px;padding:16px;box-shadow:var(--shadow);transition:transform .15s,border-color .15s}
.chapgrid a:hover{transform:translateY(-2px);border-color:var(--brand)}
.chapgrid .no{font-size:12px;font-weight:700;color:var(--brand);letter-spacing:.08em}
.chapgrid b{display:block;font-size:18px;margin:2px 0 4px;line-height:1.3}
.chapgrid span{color:var(--muted);font-size:14.5px;line-height:1.5;display:block}
.chapgrid .pr{height:5px;background:var(--line);border-radius:4px;margin-top:12px;overflow:hidden}
.chapgrid .pr i{display:block;height:100%;background:var(--brand);width:0}

/* tree */
.tree{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:20px;box-shadow:var(--shadow)}
.tree .crumbs{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:14px;font-size:14px;color:var(--muted)}
.tree .crumbs span{background:var(--brand-soft);color:var(--ink);border-radius:999px;padding:2px 10px}
.tree h2{margin:.2em 0 .6em}
.tree .opt{display:block;width:100%;text-align:left;margin:8px 0;padding:12px 14px;border:1px solid var(--line);border-radius:10px;background:var(--bg);color:var(--ink);font:inherit;cursor:pointer}
.tree .opt:hover{border-color:var(--brand);background:var(--brand-soft)}
.tree .res{border-left:5px solid var(--ok-line);background:var(--ok-bg);border-radius:0 10px 10px 0;padding:6px 16px 10px}
.tree .row{display:flex;gap:8px;flex-wrap:wrap;margin-top:16px}
.results .hit{display:block;text-decoration:none;color:var(--ink);background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin:10px 0}
.results .hit:hover{border-color:var(--brand)}
.results .hit small{color:var(--brand);font-weight:700}
.results mark{background:#ffe08a;color:#000;border-radius:3px;padding:0 2px}

/* lightbox */
#lb{position:fixed;inset:0;background:rgba(0,0,0,.86);display:none;z-index:100;padding:20px;overflow:auto;cursor:zoom-out}
#lb.on{display:block}
#lb img{display:block;margin:0 auto;max-width:min(1500px,100%);background:#fff;border-radius:8px}
#lb p{color:#fff;text-align:center;margin:10px auto 0}

footer.foot{max-width:780px;margin:50px auto 0;padding-top:20px;border-top:1px solid var(--line);color:var(--muted);font-size:14px}

@media (max-width:960px){
  .shell{grid-template-columns:1fr}
  #menuBtn{display:inline-block}
  nav.side{position:fixed;left:0;top:61px;bottom:0;width:min(86vw,330px);background:var(--panel);z-index:50;transform:translateX(-102%);transition:transform .2s;box-shadow:var(--shadow);height:auto}
  body.menu nav.side{transform:none}
  body.menu:after{content:"";position:fixed;inset:61px 0 0 0;background:rgba(0,0,0,.35);z-index:45}
  .top .brand small{display:none}
}
@media (max-width:560px){
  body{font-size:16.5px}
  .top .brand span.tt{display:none}
  .search{flex:1 1 auto}
}
@media print{
  .top,nav.side,.pager,.btn,pre .copy,#lb{display:none!important}
  .shell{display:block}
  body{background:#fff;color:#000}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}