*{box-sizing:border-box}
:root{--bg:#f6f8fb;--panel:#ffffff;--panelAlt:#f8fafc;--ink:#172033;--heading:#0f172a;--muted:#64748b;--line:#d8e0ea;--soft:#edf3fb;--hero:linear-gradient(135deg,#ffffff 0%,#eef6ff 62%,#e8f7ef 100%);--controlBg:rgba(255,255,255,.94);--buttonBg:#fff;--buttonHover:#f8fbff;--blue:#2563eb;--blueDark:#1d4ed8;--green:#15803d;--greenSoft:#dcfce7;--greenInk:#14532d;--red:#b42318;--redSoft:#fee4e2;--redInk:#7f1d1d;--dangerBg:#fff7f6;--dangerLine:#f3b3ae;--shadow:0 14px 34px rgba(30,41,59,.09)}
body[data-theme="dark"]{--bg:#0f172a;--panel:#172033;--panelAlt:#111827;--ink:#e5edf8;--heading:#f8fafc;--muted:#9fb0c7;--line:#334155;--soft:#1e293b;--hero:linear-gradient(135deg,#111827 0%,#172554 58%,#0f2f24 100%);--controlBg:rgba(15,23,42,.94);--buttonBg:#1e293b;--buttonHover:#263448;--blue:#60a5fa;--blueDark:#93c5fd;--green:#4ade80;--greenSoft:#12351f;--greenInk:#bbf7d0;--red:#f87171;--redSoft:#3b171b;--redInk:#fecaca;--dangerBg:#2a1518;--dangerLine:#7f1d1d;--shadow:0 16px 40px rgba(0,0,0,.28)}
body{margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,sans-serif;background:var(--bg);color:var(--ink)}
button,select,textarea,input{font:inherit}
button{touch-action:manipulation}
.hero{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:24px;padding:34px 40px;background:var(--hero);border-bottom:1px solid var(--line)}
.eyebrow{color:var(--blueDark);text-transform:uppercase;letter-spacing:.12em;font-size:12px;font-weight:800;margin:0 0 10px}
.hero h1{font-size:44px;line-height:1.02;margin:0 0 12px;letter-spacing:0;color:var(--heading)}
.sub{max-width:760px;color:var(--muted);font-size:17px;margin:0}
.timerCard,.stat,.bucket,.questionCard,.learnBox{background:var(--panel);border:1px solid var(--line);box-shadow:var(--shadow);border-radius:8px}
.timerCard{padding:22px;display:flex;flex-direction:column;justify-content:center}
.timerCard span,.stat span{color:var(--muted);font-size:12px;text-transform:uppercase;letter-spacing:.08em;font-weight:800}
.timerCard strong{font-size:32px;margin:8px 0;color:var(--heading)}
.timerCard small{color:var(--muted)}
.dashboard{display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:14px;padding:22px 40px}
.stat{padding:18px}
.stat strong{display:block;font-size:28px;margin-top:8px;color:var(--heading)}
.bar{height:10px;background:var(--soft);border-radius:99px;overflow:hidden;margin-top:12px}
.bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,#2563eb,#16a34a);border-radius:inherit;transition:.25s}
.planner{padding:0 40px 20px}
.sectionHead{display:flex;justify-content:space-between;gap:18px;align-items:end;margin-bottom:12px}
.planner h2,.questionSummary h2{margin:0;color:var(--heading)}
.planner p{color:var(--muted);margin:6px 0 0}
.bucketGrid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px}
.bucket{padding:16px;cursor:pointer;transition:.16s;background:var(--panel)}
.bucket:hover{transform:translateY(-2px);border-color:#93b4f7}
.bucket.active{outline:3px solid rgba(37,99,235,.18);border-color:#2563eb}
.bucket h3{margin:6px 0 8px;font-size:17px}
.bucket p{color:var(--muted);min-height:62px;margin:0 0 8px}
.bucket ul{padding-left:18px;margin:12px 0 0}
.bucket li{margin:5px 0;color:var(--ink)}
.tiny{font-size:12px;color:var(--muted);font-weight:700}
.controls{position:sticky;top:0;z-index:10;display:flex;gap:10px;flex-wrap:wrap;align-items:center;background:var(--controlBg);backdrop-filter:blur(12px);border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:12px 40px}
.controls button,.controls select,.controls input,.actions button{background:var(--buttonBg);color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:10px 12px;cursor:pointer;min-height:42px}
.controls select{width:min(100%,320px);max-width:100%;min-width:0}
.controls input{cursor:text;min-width:220px;flex:1;max-width:360px}
.controls button:hover,.actions button:hover{border-color:#93b4f7;background:var(--buttonHover)}
.controls button.active,.actions .primary{background:var(--blue);border-color:var(--blue);color:#fff}
.themeToggle{font-weight:700}
.danger{margin-left:auto;color:var(--red)!important;border-color:var(--dangerLine)!important;background:var(--dangerBg)!important}
.studyPanel{padding:24px 40px 60px}
.questionSummary{display:flex;justify-content:space-between;align-items:center;gap:16px;margin-bottom:16px;background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:16px 18px;box-shadow:var(--shadow)}
.questionSummary strong{font-size:24px;color:var(--blueDark)}
.bucketBreak{margin:22px 0 10px;padding:10px 2px;border-bottom:1px solid var(--line)}
.bucketBreak span{font-size:12px;text-transform:uppercase;letter-spacing:.1em;color:var(--blueDark);font-weight:800}
.bucketBreak h3{margin:4px 0 0;font-size:21px}
.learnGrid{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.learnBox{padding:18px}
.learnBox li{margin:8px 0;color:var(--ink)}
.questionCard{padding:20px;margin-bottom:14px}
.questionCard.mastered{border-color:#86efac;background:linear-gradient(0deg,var(--panel),var(--greenSoft))}
.questionCard.missed{border-color:#fca5a5;background:linear-gradient(0deg,var(--panel),var(--redSoft))}
.top{display:flex;justify-content:space-between;gap:12px;align-items:center}
.badge{background:#e8f0ff;color:#1d4ed8;border:1px solid #bfdbfe;padding:5px 9px;border-radius:999px;font-size:12px;font-weight:800}
.source{color:var(--muted);font-size:12px;text-align:right}
.questionCard h3{font-size:20px;line-height:1.35;margin:14px 0}
.codeBlock,.solution{background:var(--panelAlt);border:1px solid var(--line);border-radius:8px;padding:14px;white-space:pre-wrap;overflow:auto;color:var(--ink)}
.choices{display:grid;gap:8px}
.choice{width:100%;text-align:left;padding:12px 13px;border-radius:8px;border:1px solid var(--line);background:var(--buttonBg);cursor:pointer;color:var(--ink)}
.choice:hover{border-color:#93b4f7;background:var(--buttonHover)}
.choice.correct{background:var(--greenSoft);border-color:#22c55e;color:var(--greenInk)}
.choice.wrong{background:var(--redSoft);border-color:#f87171;color:var(--redInk)}
.choice:disabled{cursor:default}
.answerBox{width:100%;min-height:142px;background:var(--buttonBg);color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:13px;margin-top:6px;resize:vertical}
.monacoAnswer{height:142px;padding:0;overflow:hidden;resize:none}
.monacoAnswer:focus-within,.answerBox:focus,.controls input:focus,.controls select:focus{outline:3px solid rgba(37,99,235,.18);border-color:var(--blue)}
.actions{display:flex;gap:10px;margin-top:14px;flex-wrap:wrap}
.explain{display:none;margin-top:14px;padding:14px;border-radius:8px;background:var(--panelAlt);color:var(--ink);border:1px solid var(--line)}
.doneMsg{background:var(--greenSoft);border:1px solid #86efac;border-radius:8px;padding:16px;margin-bottom:16px;color:var(--greenInk)}
.pill{display:inline-block;font-size:12px;color:#1e3a8a;background:#e8f0ff;border:1px solid #bfdbfe;padding:5px 9px;border-radius:999px;margin:4px}
button:focus-visible,select:focus-visible,input:focus-visible,textarea:focus-visible{outline:3px solid rgba(37,99,235,.28);outline-offset:2px}
@media(max-width:1000px){.hero,.dashboard,.bucketGrid,.learnGrid{grid-template-columns:1fr}.hero,.dashboard,.planner,.controls,.studyPanel{padding-left:20px;padding-right:20px}.hero h1{font-size:34px}.danger{margin-left:0}.controls input{max-width:none;min-width:180px}.bucket p{min-height:0}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;scroll-behavior:auto!important;transition-duration:.01ms!important}}