:root{--bg:#f6f7fb;--card:#fff;--text:#1d2433;--muted:#6b7385;--border:#e3e6ee;--primary:#4f6bed;--code:#0f172a;--codefg:#e2e8f0;--j:#16a34a;--m:#d97706;--s:#dc2626}
:root[data-theme=dark]{--bg:#0e1117;--card:#161b24;--text:#e6e9f0;--muted:#8b93a7;--border:#262d3b;--primary:#7b92ff;--code:#0a0d13}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);font:16px/1.6 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif}
.top{position:sticky;top:0;z-index:20;background:var(--card)}
.topbar{display:flex;align-items:center;gap:12px;padding:10px 16px;background:var(--card);border-bottom:1px solid var(--border)}
.topbar h1{font-size:18px;margin:0;flex:1}
.icon-btn.lang-btn{width:auto;padding:0 12px;font-size:14px;font-weight:700}
.icon-btn{background:none;border:1px solid var(--border);color:var(--text);border-radius:8px;font-size:18px;width:40px;height:40px;cursor:pointer}
.layout{display:flex;max-width:1200px;margin:0 auto}
.sidebar{width:270px;flex-shrink:0;padding:16px;position:sticky;top:108px;align-self:flex-start;height:calc(100vh - 108px);overflow:auto}
.sidebar a{display:flex;align-items:center;gap:8px;padding:9px 12px;border-radius:8px;color:var(--text);text-decoration:none;font-size:15px}
.sidebar a:hover{background:var(--border)}
.sidebar a.active{background:var(--primary);color:#fff}
.sidebar a small{margin-left:auto;opacity:.75;font-size:12px}
.side-foot{margin-top:16px}
.link-btn{background:none;border:0;color:var(--muted);cursor:pointer;text-decoration:underline;font-size:13px}
.main{flex:1;min-width:0;padding:16px 20px 60px}
.controls{display:flex;flex-direction:column;gap:10px}
#search{width:100%;padding:11px 14px;font-size:16px;border:1px solid var(--border);border-radius:10px;background:var(--card);color:var(--text)}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip,.btn{border:1px solid var(--border);background:var(--card);color:var(--text);border-radius:999px;padding:6px 14px;font-size:14px;cursor:pointer}
.btn{border-radius:8px}
.chip.active{background:var(--primary);border-color:var(--primary);color:#fff}
.row{display:flex;align-items:center;gap:8px;flex-wrap:wrap}.spacer{flex:1}.muted{color:var(--muted);font-size:14px}
h2{margin:22px 0 8px}
.progress{height:6px;background:var(--border);border-radius:99px;overflow:hidden;margin-bottom:16px}
.progress div{height:100%;width:0;background:var(--j);transition:width .3s}
.card{background:var(--card);border:1px solid var(--border);border-radius:12px;margin-bottom:10px;overflow:hidden}
.card.done{border-left:4px solid var(--j)}
.card-head{display:flex;align-items:flex-start;gap:10px;padding:14px;cursor:pointer}
.card-head h3{margin:0;font-size:16px;font-weight:600;flex:1}
.badge{font-size:11px;font-weight:700;text-transform:uppercase;padding:2px 8px;border-radius:99px;color:#fff;flex-shrink:0;margin-top:2px}
.badge.junior{background:var(--j)}.badge.mid{background:var(--m)}.badge.senior{background:var(--s)}
.chip.lv-junior.active{background:var(--j);border-color:var(--j)}.chip.lv-mid.active{background:var(--m);border-color:var(--m)}.chip.lv-senior.active{background:var(--s);border-color:var(--s)}
.star{background:none;border:0;font-size:20px;cursor:pointer;color:var(--muted);padding:0}
.star.on{color:#f59e0b}
.answer{display:none;padding:0 16px 16px;border-top:1px solid var(--border)}
.card.open .answer{display:block}
.answer p{margin:12px 0}.answer ul{padding-left:22px}
.answer code{background:var(--border);padding:1px 6px;border-radius:5px;font-size:.9em}
.answer pre{background:var(--code);color:var(--codefg);padding:12px 14px;border-radius:8px;overflow:auto;font-size:13.5px;line-height:1.5}
.answer pre code{background:none;padding:0;color:inherit}
.answer-foot{display:flex;gap:8px;margin-top:8px}
.empty{text-align:center;color:var(--muted);padding:40px 0}
.backdrop{display:none}
#menuBtn{display:none}
@media(max-width:820px){
  #menuBtn{display:block}
  .sidebar{position:fixed;top:108px;left:0;bottom:0;height:auto;width:280px;max-width:85vw;background:var(--card);z-index:30;transform:translateX(-100%);transition:transform .2s;border-right:1px solid var(--border)}
  body.menu-open .sidebar{transform:none}
  body.menu-open .backdrop{display:block;position:fixed;inset:108px 0 0 0;background:#0007;z-index:25}
  .main{padding:12px 12px 60px}
}

.tabs{display:flex;gap:4px;padding:0 12px;overflow-x:auto;border-bottom:1px solid var(--border);scrollbar-width:none}
.tabs::-webkit-scrollbar{display:none}
.tab{padding:11px 14px;white-space:nowrap;color:var(--muted);text-decoration:none;font-size:15px;border-bottom:3px solid transparent;margin-bottom:-1px}
.tab.active{color:var(--primary);border-color:var(--primary);font-weight:600}
.sidebar .grp{margin-top:10px;font-weight:700}
.sidebar .sub{padding-left:22px;font-size:14px}
.sidebar a .tick{margin-left:auto;color:var(--j)}
.doc{max-width:860px}
.doc h2.doc-title{margin:6px 0 4px;font-size:26px;line-height:1.25}
.doc .doc-sub{color:var(--muted);margin:0 0 16px;font-size:14px}
.doc h3.s2{margin:28px 0 8px;font-size:20px;padding-bottom:6px;border-bottom:1px solid var(--border)}
.doc h4.s3{margin:18px 0 4px;font-size:16px;color:var(--primary)}
.doc p{margin:10px 0}.doc ul,.doc ol{padding-left:24px}.doc li{margin:4px 0}
.doc code.ic{background:var(--border);padding:1px 6px;border-radius:5px;font-size:.9em}
.note{background:color-mix(in srgb,var(--primary) 10%,var(--card));border-left:4px solid var(--primary);padding:10px 14px;border-radius:8px;margin:12px 0}
.codewrap{position:relative;margin:12px 0}
.codewrap pre{background:var(--code);color:var(--codefg);padding:14px;border-radius:10px;overflow:auto;font-size:13.5px;line-height:1.5;margin:0;tab-size:2}
.codewrap .copy{position:absolute;top:6px;right:6px;font-size:12px;padding:3px 9px;border-radius:6px;border:1px solid #475569;background:#1e293b;color:#cbd5e1;cursor:pointer;opacity:.85}
.tbl{overflow-x:auto;margin:12px 0}
.tbl table{border-collapse:collapse;width:100%;font-size:14.5px}
.tbl th,.tbl td{border:1px solid var(--border);padding:8px 10px;text-align:left;vertical-align:top}
.tbl th{background:var(--primary);color:#fff}
.tbl tr:nth-child(even) td{background:color-mix(in srgb,var(--border) 35%,transparent)}
.pager{display:flex;gap:8px;justify-content:space-between;margin:32px 0 0;flex-wrap:wrap}
.pager .btn{max-width:48%;text-align:left}
.tk-c{color:#94a3b8}.tk-s{color:#a5d6a7}.tk-k{color:#c792ea}
.doc-read{margin-top:24px}
@media(max-width:820px){.doc h2.doc-title{font-size:22px}.tab{padding:10px 12px;font-size:14px}}