#init-content {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 25px 50px;
    border: 4px solid #ccc;
    border-radius: 12px;
    text-align: center;
}

.input-content {
    margin-top: 20px;
    text-align: left;
}

#start-game-btn {
    width: 100px;
    height: 30px;
    line-height: 30px;
    margin-top: 20px;
    background-color: #00ccee;
    border-width: 0;
    border-radius: 5px;
    color: #fff;
    text-align: center;
}

#score-container {
    display: none;
    position: fixed;
    top: calc(50% - 240px);
    left: 50%;
    transform: translate(-50%, 0);
    font-weight: bold;
}

#introduce-container {
    display: none;
    position: fixed;
    top: 50%;
    left: calc(50% + 250px);
    transform: translate(0, -50%);
    font-weight: bold;
}

#introduce-container div {
    margin-top: 12px;
}

.introduce-snake-head {
    position: relative;
    display: inline-block;
    width: 16px;
    height: 16px;
    vertical-align: middle;
    border-radius: 50%;
    background-color: #ffa500;
}

.introduce-snake-head::after{
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    width: 0;
    height: 0;
    margin-top: -4px;
    border-top: 4px solid transparent;
    border-bottom: 4px solid transparent;
    border-left: 6px solid #fff;
}

.introduce-food {
    display: inline-block;
    width: 12px;
    height: 12px;
    margin-top: 4px;
    margin-left: 4px;
    vertical-align: middle;
    border-radius: 50%;
    background-color: red;
}

.introduce-obstacle {
    display: inline-block;
    width: 16px;
    height: 16px;
    margin: 2px;
    vertical-align: middle;
    background-color: burlywood;
}

#container {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    border: 5px solid rosybrown;
    overflow: hidden;
}

.snake {
    position: absolute;
}

.snake-item {
    position: absolute;
    width: 16px;
    height: 16px;
    margin: 2px;
    border-radius: 50%;
    background-color: rgb(150, 51, 26);
}

.snake-item:first-child{
    background-color: #ffa500;
}

.snake-item:first-child::after{
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    width: 0;
    height: 0;
    margin-top: -4px;
    border-top: 4px solid transparent;
    border-bottom: 4px solid transparent;
    border-left: 6px solid #fff;
}

.obstacle {
    position: absolute;
    width: 16px;
    height: 16px;
    margin: 2px;
    background-color: burlywood;
}

.food {
    position: absolute;
    width: 12px;
    height: 12px;
    margin-top: 4px;
    margin-left: 4px;
    border-radius: 50%;
    background-color: red;
}

#game-over-container {
    display: none;
    position: fixed;
    top: 50%;
    left: 50%;
    width: 400px;
    height: 400px;
    transform: translate(-50%, -50%);
    text-align: center;
    z-index: 100;
    background-color: rgba(0,0,0,0.7);
}

#game-over-container p {
    font-size: 28px;
    color: #fff;
}

.game-over-text {
    margin-top: 80px;
}

#restart-btn {
    width: 100px;
    height: 30px;
    line-height: 30px;
    margin-top: 20px;
    background-color: #ffa500;
    border-width: 0;
    border-radius: 5px;
    color: #fff;
    text-align: center;
}

#exit-btn {
    width: 100px;
    height: 30px;
    line-height: 30px;
    margin-top: 20px;
    margin-left: 20px;
    background-color: #fff;
    border-width: 0;
    border-radius: 5px;
    color: #000;
    text-align: center;
}


/* 扩展：游戏排行榜 */
#rank-container {
    position: fixed;
    top: 50%;
    right: calc(50% + 250px);
    width: 300px;
    transform: translate(0, -50%);
    padding: 10px 20px;
    border-radius: 12px;
    border: 3px solid #ffa500;
    font-weight: bold;
}

#rank-container p {
    text-align: center;
    color: crimson;
    font-size: 28px;
}