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

body {
    background-color: #000;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    font-family: Arial, sans-serif;
}

.game-container {
    position: relative;
}

#gameCanvas {
    border: 2px solid #333;
    background-color: #000;
}

.score {
    position: absolute;
    top: 20px;
    left: 20px;
    color: #fff;
    font-size: 24px;
    font-weight: bold;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
}

.side-panel {
    position: absolute;
    top: 50%;
    width: 220px;
    color: #fff;
    background: rgba(0,0,0,0.7);
    border: 2px solid #f33;
    border-radius: 10px;
    padding: 24px 18px 24px 18px;
    font-size: 18px;
    transform: translateY(-50%);
    z-index: 10;
    box-shadow: 0 0 10px #000;
}
.left-panel {
    left: 30px;
    text-align: left;
}
.right-panel {
    right: 30px;
    text-align: left;
}
.side-panel h3 {
    font-size: 22px;
    margin-bottom: 12px;
    color: #ffb300;
}
.side-panel ul {
    list-style: disc inside;
    margin-left: 0;
}
.side-panel li {
    margin-bottom: 8px;
}

/* 开始按钮样式提升z-index */
.game-container button {
    z-index: 100;
    transition: background 0.2s, transform 0.2s;
}
.game-container button:hover {
    background: #3399ff;
    transform: scale(1.08);
}

/* side-panel 响应式优化 */
@media (max-width: 1200px) {
    .side-panel {
        width: 120px;
        font-size: 13px;
        padding: 10px 6px;
    }
    .side-panel h3 {
        font-size: 15px;
        margin-bottom: 6px;
    }
}
@media (max-width: 900px) {
    .side-panel {
        display: none;
    }
}

/* 分数浮动提示 */
.score-float {
    position: absolute;
    color: #ffeb3b;
    font-size: 22px;
    font-weight: bold;
    pointer-events: none;
    text-shadow: 1px 1px 6px #000, 0 0 10px #fff;
    opacity: 0.9;
    animation: floatUp 1s ease-out forwards;
    z-index: 99;
}
@keyframes floatUp {
    0% { opacity: 1; transform: translateY(0); }
    100% { opacity: 0; transform: translateY(-40px); }
}

/* 飞机和敌机阴影 */
.plane-shadow {
    filter: drop-shadow(0 0 8px #1e90ff);
}
.enemy-shadow {
    filter: drop-shadow(0 0 8px #ff4500);
}

.css-particle {
    position: absolute;
    left: 28px;
    top: 28px;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    opacity: 0.85;
    animation: particle-explode 0.9s cubic-bezier(.2,.7,.4,1) forwards;
}
@keyframes particle-explode {
    0% { transform: translate(0,0) scale(1); opacity: 1; }
    70% { opacity: 1; }
    100% {
        transform: translate(calc(cos(var(--angle)) * var(--dist)), calc(sin(var(--angle)) * var(--dist))) scale(0.5);
        opacity: 0;
    }
}