:root{color-scheme:light;--ink: #1c1916;--muted: #5c564e;--line: #d9d1c7;--paper: #f6f1ea;--card: #fffcf7;--accent: #215c4e;--accent-soft: #e4f0eb;--wrong: #8f2d2d;--wrong-soft: #f8e8e6;--ok: #215c4e}*{box-sizing:border-box}html,body{margin:0;min-height:100%;background:var(--paper);color:var(--ink);font-family:Iwanami Mincho,Songti TC,"Noto Serif TC",PMingLiU,serif}body{font-size:17px;line-height:1.6}#app{min-height:100vh}button,input,select{font:inherit}.wrap{width:min(920px,calc(100% - 32px));margin:0 auto;padding:28px 0 64px}.top{display:flex;justify-content:space-between;gap:16px;align-items:baseline;margin-bottom:28px}.brand{font-size:13px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted)}.brand strong{display:block;margin-top:4px;font-size:22px;letter-spacing:0;color:var(--ink);text-transform:none}.nav{display:flex;gap:8px;flex-wrap:wrap}.nav button,.btn{border:1px solid var(--line);background:var(--card);color:var(--ink);padding:8px 14px;border-radius:999px;cursor:pointer}.nav button.active,.btn.primary{background:var(--accent);border-color:var(--accent);color:#fff}.btn.ghost{background:transparent}.hero{background:var(--card);border:1px solid var(--line);border-radius:20px;padding:28px;margin-bottom:20px}.hero h1{margin:0 0 8px;font-size:34px;font-weight:600}.hero p{margin:0;color:var(--muted)}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:12px}.tile{text-align:left;background:var(--card);border:1px solid var(--line);border-radius:16px;padding:18px;cursor:pointer}.tile:hover{border-color:var(--accent)}.tile small{display:block;color:var(--muted);margin-top:6px}.meta{display:flex;justify-content:space-between;gap:12px;color:var(--muted);font-size:14px;margin-bottom:16px}.stem{font-size:20px;margin:0 0 20px}.options{display:grid;gap:10px}.option{text-align:left;background:var(--card);border:1px solid var(--line);border-radius:14px;padding:12px 14px;cursor:pointer}.option.selected{border-color:var(--accent);background:var(--accent-soft)}.option.right{border-color:var(--ok);background:var(--accent-soft)}.option.wrong{border-color:var(--wrong);background:var(--wrong-soft)}.option .letter{font-weight:700;margin-right:8px}.explain{margin-top:16px;padding:14px 16px;border-radius:14px;background:var(--accent-soft)}.bar{display:flex;gap:8px;flex-wrap:wrap;margin-top:20px}.notes{background:var(--card);border:1px solid var(--line);border-radius:20px;padding:8px 28px 36px}.notes h2,.notes h3{font-weight:650}.notes table{width:100%;border-collapse:collapse;margin:12px 0 20px}.notes td,.notes th{border-bottom:1px solid var(--line);padding:6px 8px;text-align:left;vertical-align:top}.notes .formula{font-family:ui-monospace,SFMono-Regular,Menlo,monospace;background:var(--paper);padding:12px 14px;border-radius:10px;overflow-x:auto;white-space:pre-wrap}.score{font-size:56px;margin:0}.muted{color:var(--muted)}.stat{display:flex;gap:18px;flex-wrap:wrap;margin:12px 0 20px}@media (max-width: 640px){.hero h1,.stem{font-size:22px}.score{font-size:40px}}@media print{.top,.bar,.nav,.tile{display:none!important}.notes{border:0;padding:0}}