:root{--bg: #0f1220;--card: #191d33;--text: #e8eaf5;--muted: #a2a7c4;--accent: #ffd166;--accent-2: #6ee7b7;color-scheme:dark}*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:radial-gradient(1200px 600px at 70% -10%,#232a52 0%,var(--bg) 55%);color:var(--text);min-height:100vh}.wrap{max-width:760px;margin:0 auto;padding:64px 20px 40px}.hero h1{font-size:clamp(2.4rem,6vw,3.4rem);margin:0 0 8px;letter-spacing:-.02em;cursor:pointer;display:inline-block}.hero h1:after{content:"?";color:var(--accent)}.tagline{font-size:1.2rem;color:var(--muted);margin:0 0 40px}.card{background:var(--card);border:1px solid rgba(255,255,255,.06);border-radius:16px;padding:24px 28px}.card h2{margin:0 0 12px;font-size:1.3rem;color:var(--accent-2)}.card p{line-height:1.6;margin:0 0 12px}.note{color:var(--muted);font-size:.95rem}.crumbs{display:flex;align-items:center;gap:12px;margin:0 0 16px;min-height:32px}.back-btn{background:none;border:1px solid rgba(255,255,255,.12);color:var(--text);border-radius:999px;padding:6px 14px;font-size:.9rem;cursor:pointer}.back-btn:hover{border-color:var(--accent);color:var(--accent)}.crumb-current{color:var(--muted);font-size:.9rem;text-transform:uppercase;letter-spacing:.06em}.eyebrow{color:var(--accent);font-size:.85rem;text-transform:uppercase;letter-spacing:.06em;margin-bottom:6px}.screen-title{margin:0 0 10px;font-size:1.6rem;color:var(--text)}.lead{color:var(--muted);line-height:1.6;margin:0 0 24px}.block{margin-bottom:28px}.block h3{font-size:1rem;color:var(--accent-2);margin:0 0 12px}.link-cards{display:grid;gap:10px}.link-card{text-align:left;background:#ffffff08;border:1px solid rgba(255,255,255,.08);border-radius:12px;padding:14px 16px;color:var(--text);cursor:pointer;display:flex;flex-direction:column;gap:4px;font-family:inherit}.link-card:hover{border-color:var(--accent);background:#ffd1660f}.link-card-title{font-weight:600}.link-card-why{color:var(--muted);font-size:.92rem;line-height:1.5}.grade-picker{text-align:center;padding:12px 0 8px}.grade-title{font-size:1.6rem;margin:0 0 6px;color:var(--text)}.grade-sub{color:var(--muted);margin:0 0 28px}.grade-group{margin-bottom:22px}.grade-group-label{color:var(--accent-2);font-size:.9rem;text-transform:uppercase;letter-spacing:.06em;margin-bottom:12px}.grade-buttons{display:flex;flex-wrap:wrap;gap:10px;justify-content:center}.grade-btn{width:60px;height:60px;border-radius:16px;border:1px solid rgba(255,255,255,.12);background:#ffffff08;color:var(--text);font-size:1.5rem;font-weight:700;font-family:inherit;cursor:pointer;transition:transform .08s,border-color .15s,background .15s}.grade-btn:hover{border-color:var(--accent);background:#ffd16614;transform:translateY(-2px)}.grade-btn--active{border-color:var(--accent);background:var(--accent);color:#241a00}.grade-chip{margin-left:auto;background:#6ee7b714;border:1px solid rgba(110,231,183,.28);color:var(--accent-2);border-radius:999px;padding:6px 14px;font-size:.9rem;font-weight:600;font-family:inherit;cursor:pointer}.grade-chip:hover{background:#6ee7b726}.explain{margin:0 0 28px}.explain-btn{background:linear-gradient(135deg,var(--accent) 0%,#ffb03a 100%);color:#241a00;border:none;border-radius:999px;padding:12px 22px;font-size:1rem;font-weight:600;font-family:inherit;cursor:pointer}.explain-btn:disabled{opacity:.6;cursor:default}.explain-text{margin:16px 0 0;padding:16px 18px;background:#6ee7b70f;border:1px solid rgba(110,231,183,.18);border-radius:12px;line-height:1.6;white-space:pre-wrap}