:root{--ink: #111;--muted: #555;--line: #ccc;--panel: #f8f8f8;--accent: #2f6fde;--accent-soft: #e6eefc;--good: #1f9d55;--good-soft: #e3f6ea;--bad: #d64545;--bad-soft: #fde8e8;--warn-soft: #fff6db;--card: #fff}*{box-sizing:border-box;margin:0;padding:0}html,body{background:#fff;color:var(--ink)}body{font-family:Arial,Helvetica,sans-serif;-webkit-text-size-adjust:100%}button{font:inherit;color:inherit;touch-action:manipulation}.app{padding:26px 34px;min-height:100vh}.muted{color:var(--muted);font-size:12px}.controls{display:flex;gap:10px 14px;align-items:center;flex-wrap:wrap;margin-bottom:14px;padding:10px 14px;border:1px solid var(--line);border-radius:6px;background:var(--panel);font-size:13px}.control-group{display:flex;align-items:center;gap:7px}.push-right{margin-left:auto}.controls select{font-size:13px;padding:3px 8px;border:1px solid #888;border-radius:4px;background:#fff}.number-options{display:inline-flex;border:1px solid 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.ink{position:static;display:block}.trainer-foot{display:flex;gap:12px;align-items:center;flex-wrap:wrap;justify-content:center}@media (max-width: 640px){.app{padding:12px 16px}.mode-teach{padding:10px 12px}.choice-buttons{grid-template-columns:repeat(2,minmax(100px,150px))}.choice-btn{height:90px;font-size:38px}.push-right{margin-left:0}.worksheet-page{padding:20px 12px}.key-list{columns:2}}