* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Arial', sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: #333;
}

.game-container {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 20px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    text-align: center;
    max-width: 900px;
    width: 100%;
}

.header {
    margin-bottom: 20px;
}

.header h1 {
    color: #4a4a4a;
    margin-bottom: 15px;
    font-size: 2.5em;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
}

.score-board {
    display: flex;
    justify-content: space-around;
    font-size: 1.2em;
    font-weight: bold;
    color: #555;
    margin-bottom: 15px;
}

.difficulty-selector {
    margin: 20px 0;
    font-size: 1.1em;
}

.difficulty-selector label {
    margin-right: 10px;
    color: #555;
}

.difficulty-selector select {
    padding: 5px 10px;
    border-radius: 5px;
    border: 1px solid #ccc;
    font-size: 1em;
}

#gameCanvas {
    border: 3px solid #4a4a4a;
    border-radius: 10px;
    background: #f0f0f0;
    display: block;
    margin: 0 auto;
}

.controls {
    margin: 20px 0;
}

.controls button {
    padding: 12px 25px;
    margin: 0 10px;
    font-size: 1.1em;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.3s ease;
    background: linear-gradient(45deg, #667eea, #764ba2);
    color: white;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
}

.controls button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
}

.controls button:active {
    transform: translateY(0);
}

.instructions {
    margin-top: 20px;
    color: #666;
    font-size: 1.1em;
}

.instructions p {
    margin: 5px 0;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .game-container {
        padding: 15px;
        margin: 10px;
    }
    
    #gameCanvas {
        width: 100%;
        height: auto;
    }
    
    .header h1 {
        font-size: 2em;
    }
    
    .score-board {
        flex-direction: column;
        gap: 10px;
    }
    
    .controls button {
        display: block;
        width: 80%;
        margin: 10px auto;
    }
}