:root{
  --bg:#111318; --panel:#1a1e27; --panel2:#222735; --line:#2e3547;
  --text:#e8eaf0; --dim:#9aa3b5; --accent:#ffd166; --accent2:#4cc9f0;
  --good:#2ec27e; --warn:#e0a95c; --bad:#e05c5c;
  --cW:#f2f3f5; --cY:#ffd500; --cG:#00a651; --cR:#d02b2b; --cB:#1268d6; --cO:#ff7a00;
  --mask:#3a4052;
}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--text);font:15px/1.5 -apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif}
header{display:flex;align-items:center;gap:18px;padding:10px 20px;border-bottom:1px solid var(--line);position:sticky;top:0;background:var(--bg);z-index:50;flex-wrap:wrap}
header h1{font-size:17px;margin:0;letter-spacing:.5px}
header h1 span{color:var(--accent)}
nav{display:flex;gap:4px;flex-wrap:wrap}
nav button{background:none;border:0;color:var(--dim);padding:8px 14px;border-radius:8px;cursor:pointer;font-size:14px}
nav button.on{background:var(--panel2);color:var(--text)}
main{max-width:1200px;margin:0 auto;padding:18px 20px 80px}
.hidden{display:none!important}
.muted{color:var(--dim)}
.pill{display:inline-block;background:var(--panel2);border:1px solid var(--line);border-radius:99px;padding:1px 10px;font-size:12px;color:var(--dim)}
button.btn{background:var(--panel2);border:1px solid var(--line);color:var(--text);padding:8px 14px;border-radius:9px;cursor:pointer;font-size:14px}
button.btn:hover{border-color:var(--dim)}
button.btn.primary{background:var(--accent);color:#20222a;border-color:var(--accent);font-weight:600}
button.btn:disabled{opacity:.45;cursor:default}
code,.alg{font-family:ui-monospace,SFMono-Regular,Menlo,monospace}
.alg{font-size:16px;letter-spacing:1px}
/* ---- pack selector ---- */
.packbar{display:flex;gap:6px;margin-bottom:14px;flex-wrap:wrap}
.packbar button{background:var(--panel);border:1px solid var(--line);color:var(--dim);padding:7px 16px;border-radius:10px;cursor:pointer;font-size:14px}
.packbar button.on{border-color:var(--accent);color:var(--text)}
.packbar button b{color:var(--text)}
.packbar button.on b{color:var(--accent)}
.packbar .sub{display:block;font-size:11px;color:var(--dim)}
/* ---- learn layout ---- */
#learnbody{display:flex;gap:18px;align-items:flex-start}
#grouplist{width:220px;flex-shrink:0;position:sticky;top:64px}
#grouplist button{display:block;width:100%;text-align:left;background:none;border:0;border-left:3px solid transparent;color:var(--dim);padding:9px 12px;cursor:pointer;font-size:14px;border-radius:0 8px 8px 0}
#grouplist button.on{color:var(--text);border-left-color:var(--accent);background:var(--panel)}
#grouplist .cnt{float:right;opacity:.6;font-size:12px}
#learnmain{flex:1;min-width:0}
.famintro{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin-bottom:16px}
.famintro h2{margin:0 0 6px;font-size:16px}
.famintro p{margin:0;color:var(--dim);font-size:14px}
#casegrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:12px}
.card{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px;cursor:pointer;transition:border-color .15s}
.card:hover{border-color:var(--accent)}
.card .cid{color:var(--accent);font-weight:700;font-size:13px}
.card .cname{font-size:13px;color:var(--dim);min-height:20px;margin:2px 0 6px}
.card svg{display:block;margin:0 auto}
.card .calg{text-align:center;font-size:13px;color:var(--accent2);margin-top:8px;word-spacing:2px}
.card .mastery{height:4px;border-radius:2px;background:var(--panel2);margin-top:8px;overflow:hidden}
.card .mastery i{display:block;height:100%;background:var(--good)}
/* ---- detail ---- */
#detail .top{display:flex;gap:24px;flex-wrap:wrap}
#detail .cubewrap{flex-shrink:0}
#detail .info{flex:1;min-width:300px}
#detail h2{margin:4px 0 2px}
.phase{display:inline-block;margin:4px 8px 4px 0;padding:6px 12px;border-radius:9px;background:var(--panel2);border:1px solid var(--line)}
.phase b{display:block;font-size:11px;color:var(--dim);font-weight:600;text-transform:uppercase;letter-spacing:.5px}
.coach{background:var(--panel);border-left:3px solid var(--accent);border-radius:0 10px 10px 0;padding:10px 14px;margin:12px 0;font-size:14px;color:#cdd3e0}
.altlist button{display:block;background:none;border:0;color:var(--accent2);cursor:pointer;font-family:ui-monospace,Menlo,monospace;font-size:14px;padding:3px 0;text-align:left}
.altlist button:hover{text-decoration:underline}
.controls{display:flex;gap:8px;align-items:center;margin-top:12px;flex-wrap:wrap}
/* ---- 3D cube ---- */
.scene{perspective:900px;user-select:none;touch-action:none;position:relative;margin:0 auto}
.cube3d{position:absolute;transform-style:preserve-3d}
.cubie{position:absolute;transform-style:preserve-3d}
.cubie .f{position:absolute;border:2px solid #0a0c10;border-radius:9%;background:#161a22;backface-visibility:hidden}
/* ---- drill ---- */
#drill .wrap{display:flex;gap:26px;flex-wrap:wrap;align-items:flex-start}
#drill .left{flex-shrink:0;text-align:center}
#drill .right{flex:1;min-width:300px}
#rectimer{font:700 34px ui-monospace,Menlo,monospace;color:var(--accent);margin:8px 0}
#answer{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px}
.grades{display:flex;gap:8px;margin-top:12px}
.grades button{flex:1;padding:10px 0;border-radius:10px;border:1px solid var(--line);background:var(--panel2);color:var(--text);cursor:pointer}
.grades .g0:hover{border-color:var(--bad)} .grades .g3:hover{border-color:var(--warn)}
.grades .g4:hover{border-color:var(--good)} .grades .g5:hover{border-color:var(--accent2)}
.kbd{font-size:11px;color:var(--dim)}
#drillopts label{margin-right:12px;font-size:13px;color:var(--dim);white-space:nowrap}
.sessline{margin-top:14px;font-size:13px;color:var(--dim)}
/* ---- timer ---- */
#timerwrap{display:flex;gap:26px;flex-wrap:wrap;align-items:flex-start}
#timerwrap .tleft{flex:1;min-width:320px;text-align:center}
#timerwrap .tright{width:300px;flex-shrink:0}
#scramline{font-family:ui-monospace,Menlo,monospace;font-size:18px;letter-spacing:1px;word-spacing:6px;background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:12px 16px;margin-bottom:10px}
#bigtime{font:700 72px ui-monospace,Menlo,monospace;margin:16px 0 4px;cursor:pointer;-webkit-user-select:none;user-select:none}
#bigtime.armed{color:var(--bad)} #bigtime.ready{color:var(--good)} #bigtime.running{color:var(--text)}
#bigtime.inspect{color:var(--warn)}
#timehint{font-size:13px;color:var(--dim);margin-bottom:14px}
#tstats{display:flex;gap:14px;justify-content:center;flex-wrap:wrap;margin:10px 0;font-size:14px}
#tstats b{color:var(--accent)}
#solvelist{list-style:none;margin:8px 0;padding:0;max-height:340px;overflow:auto;text-align:left}
#solvelist li{display:flex;gap:8px;align-items:center;padding:5px 8px;border-bottom:1px solid var(--line);font-family:ui-monospace,Menlo,monospace;font-size:14px}
#solvelist .n{color:var(--dim);width:34px}
#solvelist .t{flex:1}
#solvelist .t.dnf{color:var(--bad)} #solvelist .t.p2{color:var(--warn)}
#solvelist button{background:none;border:0;color:var(--dim);cursor:pointer;font-size:12px;padding:2px 5px}
#solvelist button:hover{color:var(--text)}
#preview svg{display:block;margin:0 auto}
/* ---- stats ---- */
.heat{display:grid;grid-template-columns:repeat(auto-fill,minmax(120px,1fr));gap:8px;margin-bottom:20px}
.hcell{background:var(--panel);border:1px solid var(--line);border-radius:10px;padding:8px 10px;cursor:pointer}
.hcell .hid{font-weight:700;font-size:12px}
.hcell .hstat{font-size:11px;color:var(--dim)}
.dot{display:inline-block;width:10px;height:10px;border-radius:50%;margin-right:6px}
.statssec h2{font-size:16px;margin:22px 0 8px}
#sparkline{margin:6px 0}
/* ---- method ---- */
.ph{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:14px 18px;margin-bottom:12px}
.ph h3{margin:0 0 4px}
.ph p{margin:4px 0;color:var(--dim);font-size:14px}
.ph .go{color:var(--accent2);background:none;border:0;cursor:pointer;font-size:14px;padding:0}
.ph .go:hover{text-decoration:underline}
footer{position:fixed;bottom:0;left:0;right:0;background:var(--bg);border-top:1px solid var(--line);padding:6px 20px;font-size:12px;color:var(--dim);display:flex;justify-content:space-between;gap:12px}
@media(max-width:760px){
  #learnbody{flex-direction:column}
  #grouplist{position:static;width:100%;display:flex;flex-wrap:wrap;gap:5px;margin-bottom:4px}
  #grouplist button{width:auto;border:1px solid var(--line);border-left:1px solid var(--line);border-radius:99px;padding:5px 12px;font-size:13px;background:var(--panel)}
  #grouplist button.on{border-color:var(--accent);color:var(--text)}
  #grouplist .cnt{float:none;margin-left:5px;font-size:11px}
  #bigtime{font-size:54px}
  #timerwrap .tright{width:100%}
  footer{position:static}
}