@import url('https://fonts.googleapis.com/css2?family=DM+Mono:wght@400;500&family=Sora:wght@300;400;600;700;800&display=swap');
:root{
  --bg:#f0f4f8;--surface:#fff;--surface2:#f8fafc;
  --border:#e2e8f0;--border-h:#cbd5e1;
  --accent:#2563eb;--accent-l:#dbeafe;
  --accent2:#7c3aed;--accent2-l:#ede9fe;
  --green:#16a34a;--green-l:#dcfce7;
  --red:#dc2626;--red-l:#fee2e2;
  --yellow:#d97706;--yellow-l:#fef3c7;
  --text:#0f172a;--text2:#475569;--muted:#94a3b8;
  --mono:'DM Mono',monospace;--sans:'Sora',sans-serif;
}
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{background:var(--bg);font-family:var(--sans);color:var(--text);min-height:100vh;display:flex;flex-direction:column;align-items:center}
body::before{content:'';position:fixed;inset:0;background-image:linear-gradient(rgba(37,99,235,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(37,99,235,.04) 1px,transparent 1px);background-size:40px 40px;pointer-events:none;z-index:0}
a{color:inherit;text-decoration:none}

/* ─── NAV BAR ─── */
.topnav{position:relative;z-index:10;width:100%;background:var(--surface);border-bottom:1px solid var(--border);padding:0 1.5rem;display:flex;align-items:center;gap:8px;height:52px;font-size:13px;color:var(--muted)}
.topnav a{color:var(--accent);transition:opacity .15s}.topnav a:hover{opacity:.75}
.topnav span{color:var(--muted)}
.topnav-right{margin-left:auto;display:flex;align-items:center;gap:12px}
.home-btn{display:flex;align-items:center;gap:6px;padding:6px 14px;border-radius:8px;background:var(--accent-l);color:var(--accent);font-weight:600;font-size:12px;border:1px solid #bfdbfe;transition:background .15s}
.home-btn:hover{background:#bfdbfe}

/* ─── TIMER ─── */
.timer-ring{display:flex;align-items:center;gap:6px;font-family:var(--mono);font-size:13px;font-weight:500}
.timer-dot{width:8px;height:8px;border-radius:50%;background:var(--green);animation:blink 1s infinite}
@keyframes blink{0%,100%{opacity:1}50%{opacity:.3}}
.timer-ring.warn .timer-dot{background:var(--yellow)}
.timer-ring.danger .timer-dot{background:var(--red)}
.timer-ring.warn{color:var(--yellow)}
.timer-ring.danger{color:var(--red)}

/* ─── BOOKMARK ─── */
.bm-btn{background:none;border:1.5px solid var(--border-h);border-radius:8px;padding:6px 10px;cursor:pointer;font-size:16px;color:var(--muted);transition:all .15s;line-height:1}
.bm-btn:hover{border-color:var(--yellow);color:var(--yellow)}
.bm-btn.active{border-color:var(--yellow);background:var(--yellow-l);color:var(--yellow)}

/* ─── QUESTION CARD ─── */
.page{position:relative;z-index:1;width:100%;max-width:760px;padding:1.75rem 1.25rem 4rem}
.q-meta{display:flex;align-items:center;gap:10px;margin-bottom:1rem;flex-wrap:wrap}
.q-badge{display:inline-flex;align-items:center;gap:6px;background:var(--accent-l);border:1px solid #bfdbfe;border-radius:99px;padding:4px 12px;font-family:var(--mono);font-size:10px;color:var(--accent);letter-spacing:.08em;text-transform:uppercase}
.diff-badge{display:inline-block;background:var(--green-l);border:1px solid #bbf7d0;border-radius:99px;padding:3px 10px;font-family:var(--mono);font-size:10px;color:var(--green);text-transform:uppercase;letter-spacing:.06em}
.q-progress{font-family:var(--mono);font-size:11px;color:var(--muted);margin-left:auto}
.progress-track{height:4px;background:var(--border);border-radius:99px;overflow:hidden;margin-bottom:1.5rem}
.progress-fill{height:100%;background:linear-gradient(90deg,var(--accent),var(--accent2));border-radius:99px;transition:width .5s cubic-bezier(.4,0,.2,1)}
.q-card{background:var(--surface);border:1px solid var(--border);border-radius:18px;padding:2rem;box-shadow:0 2px 12px rgba(0,0,0,.06);animation:slideIn .35s ease both}
@keyframes slideIn{from{opacity:0;transform:translateY(12px)}to{opacity:1;transform:translateY(0)}}
.q-topic-tag{display:inline-block;background:var(--accent2-l);border:1px solid rgba(124,58,237,.18);color:var(--accent2);font-size:10px;font-family:var(--mono);padding:3px 10px;border-radius:99px;letter-spacing:.06em;text-transform:uppercase;margin-bottom:1rem}
.q-text{font-size:18px;font-weight:600;line-height:1.55;letter-spacing:-.01em;color:var(--text)}

/* ─── OPTIONS ─── */
.options{display:flex;flex-direction:column;gap:10px;margin-top:1.5rem}
.opt{display:flex;align-items:flex-start;gap:14px;background:var(--surface2);border:1.5px solid var(--border);border-radius:12px;padding:14px 16px;cursor:pointer;transition:border-color .15s,background .15s,transform .1s,box-shadow .15s;font-size:14.5px;line-height:1.5;text-align:left;color:var(--text2);font-family:var(--sans);width:100%}
.opt:hover:not(:disabled){border-color:var(--accent);background:var(--accent-l);transform:translateX(3px);box-shadow:0 2px 8px rgba(37,99,235,.1)}
.opt:disabled{cursor:default;transform:none}
.opt-key{flex-shrink:0;width:28px;height:28px;border-radius:7px;background:#f1f5f9;border:1.5px solid var(--border-h);display:flex;align-items:center;justify-content:center;font-family:var(--mono);font-size:11px;font-weight:500;color:var(--text2);transition:all .15s}
.opt.correct{background:var(--green-l);border-color:#86efac}
.opt.correct .opt-key{background:#bbf7d0;border-color:var(--green);color:var(--green)}
.opt.wrong{background:var(--red-l);border-color:#fca5a5}
.opt.wrong .opt-key{background:#fecaca;border-color:var(--red);color:var(--red)}
.opt.reveal{background:#f0fdf4;border-color:#86efac}
.opt.reveal .opt-key{background:#bbf7d0;border-color:var(--green);color:var(--green)}

/* ─── EXPLANATION ─── */
.explanation{background:#f8faff;border:1px solid #bfdbfe;border-left:4px solid var(--accent);border-radius:0 12px 12px 0;padding:1.25rem 1.5rem;margin-top:1.25rem;font-size:14px;line-height:1.75;color:var(--text2);animation:slideIn .3s ease both}
.explanation .verdict{font-weight:600;font-size:12px;text-transform:uppercase;letter-spacing:.1em;margin-bottom:.5rem;font-family:var(--mono)}
.verdict.v-correct{color:var(--green)}
.verdict.v-wrong{color:var(--red)}
.explanation strong{color:var(--text);font-weight:600}
.explanation code{background:#e2e8f0;padding:2px 6px;border-radius:4px;font-family:var(--mono);font-size:12px}

/* ─── NAV BUTTONS ─── */
.nav-row{display:flex;gap:12px;margin-top:1.5rem;justify-content:space-between;align-items:center}
.btn{padding:11px 26px;border-radius:10px;font-size:14px;font-weight:600;font-family:var(--sans);cursor:pointer;transition:all .15s;border:1.5px solid transparent}
.btn-primary{background:var(--accent);color:#fff;border-color:var(--accent)}
.btn-primary:hover{background:#1d4ed8}
.btn-ghost{background:transparent;color:var(--text2);border-color:var(--border-h)}
.btn-ghost:hover{color:var(--text);border-color:var(--accent);background:var(--accent-l)}
.btn-sm{padding:8px 18px;font-size:13px}

/* ─── TOPIC GRID (home) ─── */
.topic-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;width:100%;max-width:1100px;padding:0 1.5rem 3rem}
.topic-card{background:var(--surface);border:1.5px solid var(--border);border-radius:18px;padding:1.5rem;cursor:pointer;transition:all .2s;text-decoration:none;display:flex;flex-direction:column;gap:10px;box-shadow:0 1px 4px rgba(0,0,0,.05)}
.topic-card:hover{transform:translateY(-3px);box-shadow:0 8px 24px rgba(0,0,0,.1)}
.tc-icon{font-size:28px;line-height:1}
.tc-badge{display:inline-block;font-size:9px;font-family:var(--mono);padding:3px 8px;border-radius:5px;font-weight:600;letter-spacing:.06em;text-transform:uppercase}
.tc-title{font-size:16px;font-weight:700;color:var(--text);line-height:1.3}
.tc-desc{font-size:12.5px;color:var(--muted);line-height:1.55}
.tc-tags{display:flex;flex-wrap:wrap;gap:5px;margin-top:4px}
.tc-tag{font-size:10px;padding:2px 8px;border-radius:5px;background:var(--surface2);border:1px solid var(--border);color:var(--text2);font-family:var(--mono)}
.tc-progress{margin-top:6px}
.tc-prog-bar{height:3px;background:var(--border);border-radius:99px;overflow:hidden;margin-top:4px}
.tc-prog-fill{height:100%;border-radius:99px;transition:width .5s}
.tc-prog-lbl{font-size:10px;color:var(--muted);font-family:var(--mono);display:flex;justify-content:space-between}

/* ─── TOPIC PAGE ─── */
.topic-hero{width:100%;padding:2.5rem 1.5rem 2rem;text-align:center;position:relative;z-index:1}
.topic-hero-icon{font-size:48px;margin-bottom:1rem}
.topic-hero-badge{display:inline-block;padding:5px 16px;border-radius:99px;font-size:11px;font-family:var(--mono);font-weight:600;letter-spacing:.08em;text-transform:uppercase;margin-bottom:1rem}
.topic-hero h1{font-size:clamp(1.5rem,4vw,2.25rem);font-weight:800;letter-spacing:-.02em;color:var(--text)}
.topic-hero p{font-size:15px;color:var(--text2);margin-top:.75rem;max-width:560px;margin-left:auto;margin-right:auto;line-height:1.65}
.topic-stats{display:flex;gap:12px;justify-content:center;flex-wrap:wrap;margin-top:1.5rem}
.t-stat{background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:10px 20px;text-align:center;min-width:90px}
.t-stat-val{font-size:20px;font-weight:700;font-family:var(--mono)}
.t-stat-lbl{font-size:10px;color:var(--muted);text-transform:uppercase;letter-spacing:.07em}

/* ─── QUESTION LIST ─── */
.q-list{width:100%;max-width:700px;padding:0 1.25rem;position:relative;z-index:1}
.q-list-item{display:flex;align-items:center;gap:14px;background:var(--surface);border:1.5px solid var(--border);border-radius:14px;padding:14px 18px;margin-bottom:10px;text-decoration:none;transition:all .15s;cursor:pointer}
.q-list-item:hover{border-color:var(--accent);background:var(--accent-l);transform:translateX(3px)}
.q-list-num{flex-shrink:0;width:32px;height:32px;border-radius:8px;background:var(--surface2);border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-family:var(--mono);font-size:12px;font-weight:500;color:var(--text2)}
.q-list-num.correct{background:var(--green-l);border-color:var(--green);color:var(--green)}
.q-list-num.wrong{background:var(--red-l);border-color:var(--red);color:var(--red)}
.q-list-text{flex:1;font-size:13.5px;color:var(--text2);line-height:1.4}
.q-list-status{font-size:11px;font-family:var(--mono);color:var(--muted)}
.q-list-bm{font-size:14px;flex-shrink:0}

/* ─── HERO (home) ─── */
.hero{width:100%;background:linear-gradient(135deg,#0f172a 0%,#1e1b4b 50%,#1e3a5f 100%);position:relative;overflow:hidden;display:flex;flex-direction:column;align-items:center}
.hero::before{content:'';position:absolute;inset:0;background-image:linear-gradient(rgba(99,179,237,.06) 1px,transparent 1px),linear-gradient(90deg,rgba(99,179,237,.06) 1px,transparent 1px);background-size:32px 32px;pointer-events:none}
.hero-inner{position:relative;z-index:1;width:100%;max-width:1100px;padding:3rem 2rem 0;display:flex;align-items:center;justify-content:space-between;gap:2rem}
.hero-text{flex:1;min-width:0}
.hero-eyebrow{display:inline-flex;align-items:center;gap:8px;background:rgba(99,179,237,.12);border:1px solid rgba(99,179,237,.3);border-radius:99px;padding:5px 14px;font-family:var(--mono);font-size:11px;color:#93c5fd;letter-spacing:.1em;text-transform:uppercase;margin-bottom:1.25rem}
.hero-eyebrow::before{content:'';width:6px;height:6px;border-radius:50%;background:#60a5fa;animation:blink 2s infinite}
.hero h1{font-size:clamp(2rem,5vw,3rem);font-weight:800;line-height:1.1;letter-spacing:-.03em;color:#fff;margin-bottom:1rem}
.hero h1 em{color:#60a5fa;font-style:normal}
.hero-sub{font-size:15px;color:#94a3b8;font-weight:300;line-height:1.7;margin-bottom:1.75rem;max-width:480px}
.hero-chips{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:2rem}
.chip{display:flex;align-items:center;gap:6px;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.12);border-radius:8px;padding:6px 12px;font-size:12px;color:#cbd5e1;font-family:var(--mono)}
.chip-dot{width:6px;height:6px;border-radius:50%}
.hero-art{flex-shrink:0;width:340px}
.hero-art svg{width:100%;height:auto}
.hero-strip{position:relative;z-index:1;width:100%;max-width:1100px;padding:1.25rem 2rem;display:flex;gap:2rem;flex-wrap:wrap;border-top:1px solid rgba(255,255,255,.07);margin-top:1.5rem}
.hstat{display:flex;align-items:center;gap:10px}
.hstat-val{font-size:15px;font-weight:700;color:#e2e8f0;font-family:var(--mono)}
.hstat-lbl{font-size:12px;color:#64748b}
.hero-wave{width:100%;overflow:hidden;line-height:0}
.hero-wave svg{display:block;width:100%;height:48px}

/* ─── SECTION HEADINGS ─── */
.section-head{width:100%;max-width:1100px;padding:2.5rem 1.5rem 1rem;position:relative;z-index:1}
.section-head h2{font-size:22px;font-weight:700;letter-spacing:-.01em;color:var(--text)}
.section-head p{font-size:14px;color:var(--muted);margin-top:.25rem}

/* ─── FEATURES SECTION ─── */
.features-wrap{width:100%;background:var(--surface);border-top:1px solid var(--border);border-bottom:1px solid var(--border);margin:1rem 0;position:relative;z-index:1}
.features-inner{max-width:1100px;margin:0 auto;padding:2.5rem 1.5rem;display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:20px}
.feat{display:flex;flex-direction:column;gap:8px}
.feat-icon{font-size:24px}
.feat-title{font-size:14px;font-weight:700;color:var(--text)}
.feat-desc{font-size:12.5px;color:var(--muted);line-height:1.6}
.feat-tag{display:inline-block;font-size:9px;font-family:var(--mono);padding:2px 8px;border-radius:4px;font-weight:600;letter-spacing:.06em;text-transform:uppercase;margin-top:2px;background:var(--yellow-l);color:var(--yellow);border:1px solid #fcd34d}

/* ─── FOOTER ─── */
footer{width:100%;background:#0f172a;margin-top:auto;position:relative;overflow:hidden}
footer::before{content:'';position:absolute;inset:0;background-image:linear-gradient(rgba(99,179,237,.04) 1px,transparent 1px),linear-gradient(90deg,rgba(99,179,237,.04) 1px,transparent 1px);background-size:28px 28px;pointer-events:none}
.footer-wave{width:100%;overflow:hidden;line-height:0}
.footer-wave svg{display:block;width:100%}
.footer-inner{position:relative;z-index:1;max-width:1100px;margin:0 auto;padding:3rem 2rem 2rem;display:grid;grid-template-columns:2fr 1fr 1fr 1fr;gap:2.5rem}
.footer-logo{display:flex;align-items:center;gap:10px;margin-bottom:1rem}
.footer-logo-icon{width:36px;height:36px;border-radius:9px;background:linear-gradient(135deg,#2563eb,#7c3aed);display:flex;align-items:center;justify-content:center;font-size:18px}
.footer-logo-text{font-size:16px;font-weight:700;color:#e2e8f0;letter-spacing:-.01em}
.footer-tagline{font-size:13px;color:#64748b;line-height:1.6;max-width:220px}
.footer-social{display:flex;gap:10px;margin-top:1.25rem}
.social-btn{width:34px;height:34px;border-radius:8px;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.1);display:flex;align-items:center;justify-content:center;color:#94a3b8;font-size:14px;text-decoration:none;transition:all .15s}
.social-btn:hover{background:rgba(37,99,235,.2);border-color:rgba(37,99,235,.4);color:#60a5fa}
.footer-col h4{font-size:12px;font-weight:600;color:#94a3b8;text-transform:uppercase;letter-spacing:.1em;font-family:var(--mono);margin-bottom:1rem}
.footer-col a{display:block;font-size:13px;color:#64748b;text-decoration:none;margin-bottom:.6rem;transition:color .15s}
.footer-col a:hover{color:#93c5fd}
.footer-bottom{position:relative;z-index:1;max-width:1100px;margin:0 auto;padding:1.25rem 2rem;border-top:1px solid rgba(255,255,255,.06);display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:1rem}
.footer-copy{font-size:12px;color:#475569;font-family:var(--mono)}
.footer-badges{display:flex;gap:8px}
.f-badge{font-size:10px;font-family:var(--mono);padding:4px 10px;border-radius:6px;font-weight:500;letter-spacing:.05em;text-transform:uppercase;border:1px solid rgba(255,255,255,.08);color:#475569}

/* ─── RESULT MINI ─── */
.result-mini{background:var(--surface);border:1px solid var(--border);border-radius:16px;padding:2rem;text-align:center;box-shadow:0 2px 12px rgba(0,0,0,.06);margin-top:1rem}
.score-ring{width:110px;height:110px;border-radius:50%;border:3px solid var(--accent);margin:0 auto 1rem;display:flex;flex-direction:column;align-items:center;justify-content:center;background:var(--accent-l)}
.score-num{font-size:32px;font-weight:700;font-family:var(--mono);color:var(--accent)}
.score-den{font-size:13px;color:var(--muted);font-family:var(--mono)}
.tier-badge{display:inline-block;padding:6px 20px;border-radius:99px;font-size:11px;font-weight:600;font-family:var(--mono);letter-spacing:.06em;text-transform:uppercase;margin-bottom:1rem}
.tier-gold{background:var(--yellow-l);color:var(--yellow);border:1.5px solid #fcd34d}
.tier-blue{background:var(--accent-l);color:var(--accent);border:1.5px solid #93c5fd}
.tier-purple{background:var(--accent2-l);color:var(--accent2);border:1.5px solid #c4b5fd}
.tier-red{background:var(--red-l);color:var(--red);border:1.5px solid #fca5a5}
.result-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin:1rem 0}
.r-stat{background:var(--surface2);border:1px solid var(--border);border-radius:10px;padding:10px;text-align:center}
.r-stat-val{font-size:22px;font-weight:700;font-family:var(--mono)}
.r-stat-lbl{font-size:10px;color:var(--muted);text-transform:uppercase;letter-spacing:.06em;margin-top:2px}

@media(max-width:720px){
  .hero-inner{flex-direction:column}
  .hero-art{width:100%;max-width:280px}
  .footer-inner{grid-template-columns:1fr 1fr}
  .footer-brand{grid-column:1/-1}
  .q-text{font-size:16px}
  .q-card{padding:1.25rem}
  .result-grid{grid-template-columns:1fr 1fr}
  .topic-grid{grid-template-columns:1fr}
}
@media(max-width:480px){
  .footer-inner{grid-template-columns:1fr}
  .topic-grid{padding:0 1rem 2rem}
}