:root{--bg: #f6f7fb;--surface: #ffffff;--border: #e5e7eb;--text: #1f2937;--muted: #6b7280;--accent: #4f46e5;--again: #ef4444;--hard: #f59e0b;--good: #10b981;--easy: #3b82f6}*{box-sizing:border-box}body{margin:0;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,PingFang TC,Microsoft JhengHei,sans-serif;background:var(--bg);color:var(--text)}.app{max-width:880px;margin:0 auto;padding:24px 20px 80px}.app-header{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px}.app-header h1{font-size:22px;margin:0;letter-spacing:-.01em}.tabs{display:flex;gap:4px;background:var(--surface);border:1px solid var(--border);border-radius:999px;padding:4px}.tab{border:0;background:transparent;padding:6px 14px;border-radius:999px;cursor:pointer;color:var(--muted);font-size:14px}.tab.active{background:var(--accent);color:#fff}.deck-selector{display:flex;flex-direction:column;gap:12px}.deck{display:flex;align-items:center;justify-content:space-between;background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:14px 16px;cursor:pointer;text-align:left;font:inherit;color:inherit;transition:border-color .15s,transform .05s}.deck:hover:not(:disabled){border-color:var(--accent)}.deck:active:not(:disabled){transform:scale(.99)}.deck:disabled{opacity:.5;cursor:default}.deck-all{background:linear-gradient(135deg,#eef2ff,#fff);border-color:#c7d2fe}.deck-name{font-weight:600;font-size:15px}.deck-counts{display:flex;gap:6px;flex-shrink:0}.badge{font-size:12px;padding:3px 8px;border-radius:999px;background:#f3f4f6;color:var(--muted);white-space:nowrap}.badge-due{background:#fef3c7;color:#92400e}.badge-new{background:#dbeafe;color:#1e40af}.deck-list{display:flex;flex-direction:column;gap:8px}.reviewer{display:flex;flex-direction:column;gap:16px}.reviewer-header{display:flex;justify-content:space-between;align-items:center}.link-btn{background:transparent;border:0;color:var(--accent);cursor:pointer;font-size:14px;padding:4px 0}.queue-count{color:var(--muted);font-size:14px}.card{background:var(--surface);border:1px solid var(--border);border-radius:16px;padding:28px 24px;min-height:280px;display:flex;flex-direction:column;gap:20px}.card-front{display:flex;flex-direction:column;align-items:center;text-align:center;gap:8px}.word{font-size:32px;font-weight:700;letter-spacing:-.02em}.pos{color:var(--muted);font-style:italic;font-size:14px}.section-tag{margin-top:8px;font-size:11px;color:var(--muted);background:#f3f4f6;padding:3px 10px;border-radius:999px}.card-back{border-top:1px dashed var(--border);padding-top:18px;display:flex;flex-direction:column;gap:14px}.definition{font-size:20px;font-weight:600;text-align:center}.example p{margin:4px 0 0;font-size:15px;color:var(--text);font-style:italic}.label{font-size:11px;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:600}.synonyms ul{margin:6px 0 0;padding-left:20px;font-size:14px;color:var(--text)}.synonyms li{margin-bottom:2px}.show-btn{width:100%;padding:14px;border-radius:12px;border:0;background:var(--accent);color:#fff;font-size:15px;font-weight:600;cursor:pointer}.rating-buttons{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}.rate{padding:12px 8px;border-radius:12px;border:0;color:#fff;font-weight:600;cursor:pointer;font-size:14px}.rate-again{background:var(--again)}.rate-hard{background:var(--hard)}.rate-good{background:var(--good)}.rate-easy{background:var(--easy)}.reviewer-empty{text-align:center;padding:60px 20px;background:var(--surface);border:1px solid var(--border);border-radius:16px}.reviewer-empty button{margin-top:16px;padding:10px 20px;border:0;background:var(--accent);color:#fff;border-radius:8px;cursor:pointer;font-size:14px}.stats h2{margin-top:0}.stat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:12px}.stat{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:16px;text-align:center}.stat-value{font-size:28px;font-weight:700;color:var(--accent)}.stat-label{font-size:12px;color:var(--muted);margin-top:4px}