/* 公共样式表 */
:root {
    --main-bg: linear-gradient(135deg, #2c3e50 0%, #3498db 100%);
    --canvas-bg: rgba(236, 240, 241, 0.9);
    --text-color: #000000;
    --text-shadow: 0 2px 4px rgba(255, 255, 255, 0.5);
    --font-primary: 'Arial', sans-serif;
}

body {
    font-family: var(--font-primary);
    background: var(--main-bg);
    color: var(--text-color);
    min-height: 100vh;
    margin: 0;
}

.game-canvas {
    background-color: var(--canvas-bg);
    border: 3px solid #34495e;
    border-radius: 5px;
}

.score-display {
    font-size: 24px;
    margin: 20px;
    text-shadow: var(--text-shadow);
    font-weight: 600;
}

#instructions {
    background-color: rgba(0, 0, 0, 0.7);
    padding: 20px;
    border-radius: 10px;
    backdrop-filter: blur(8px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    color: var(--text-color);
    text-shadow: var(--text-shadow);
}

.game-button {
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background-color 0.3s;
}

.primary-btn {
    background-color: #3498db;
    color: white;
}

.primary-btn:hover {
    background-color: #2980b9;
}

.secondary-btn {
    background-color: #27ae60;
    color: white;
}

.secondary-btn:hover {
    background-color: #219a52;
}