:root{--bg-color: #f5f5f5;--text-color: #333;--btn-bg: #fff;--btn-border: #ccc;--btn-hover: #e0e0e0;--accent-color: #007bff;--error-color: #dc3545;--success-color: #28a745}body{font-family:-apple-system,BlinkMacSystemFont,Helvetica Neue,PingFang SC,Microsoft YaHei,Source Han Sans SC,Noto Sans CJK SC,WenQuanYi Micro Hei,sans-serif;background-color:var(--bg-color);color:var(--text-color);display:flex;flex-direction:column;align-items:center;justify-content:center;min-height:100vh;margin:0;user-select:none}.container{background:white;padding:2rem;border-radius:12px;box-shadow:0 4px 12px #0000001a;text-align:center;max-width:500px;width:90%}h1{margin-top:0;font-size:1.5rem}.status-bar{display:flex;justify-content:space-between;margin-bottom:1.5rem;font-size:.9rem;color:#666}.question-area{margin:2rem 0}.question-type{font-size:1.2rem;font-weight:700;margin-bottom:.5rem;color:var(--accent-color)}#question{font-size:1.5rem;margin-bottom:1rem}.controls{margin-bottom:1.5rem}button{background:var(--btn-bg);border:1px solid var(--btn-border);padding:10px 20px;border-radius:6px;cursor:pointer;font-size:1rem;transition:all .2s;margin:5px}button:hover:not(:disabled){background:var(--btn-hover);border-color:#999}button:disabled{opacity:.5;cursor:not-allowed}#options-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;justify-items:center}#options-grid button{width:100%;min-width:60px;min-height:75px;padding:15px 5px;font-weight:700;font-size:1.5em}#options-grid button.standard{font-size:1em}#options-grid{grid-template-columns:repeat(4,1fr)}#feedback{height:20px;margin-top:10px;font-weight:700}#feedback.correct{color:var(--success-color)}#feedback.wrong{color:var(--error-color)}.hidden{display:none}.mode-select button{display:block;width:100%;margin:10px 0;padding:15px;font-size:1.1rem}#lives{color:var(--error-color);font-weight:700}#final-score{font-size:1.5rem}a{color:#007bff;text-decoration:none;transition:color .2s}a:hover{color:#0056b3}