* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
    font-family: Georgia, Times, 'Microsoft Yahei', serif;
// 取消默认鼠标双击选中状态
-webkit-user-select: none;
    /* Safari 和 Chrome */
    -moz-user-select: none;
    /* 老的 Firefox */
    -o-user-select: none;
    /* Opera */
    user-select: none;
}

html,
body {
    width: 100%;
}


/* 滚动背景图 */

.sky_img {
    position: relative;
    width: 100%;
    height: 600px;
    background: url('../img/sky.png');
    overflow: hidden;
}


/* 小鸟图片 */

.bird {
    width: 30px;
    height: 40px;
    position: absolute;
    left: 50%;
    top: 270px;
    transform: translateX(-50%);
}


/* 开始游戏 */

h2 {
    width: 100px;
    height: 50px;
    cursor: pointer;
    margin: 350px auto;
}


/* 分数 */

.score {
    color: yellow;
    font-weight: bold;
    font-size: 30px;
    position: fixed;
    top: 0;
    left: 50%;
    z-index: 99;
}


/* 遮罩层 */

.mask {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    display: none;
    z-index: 999;
    background-color: rgba(0, 0, 0, .6);
}


/* 弹框 */

.sucess {
    width: 300px;
    height: 300px;
    font-weight: bold;
    margin: 150px -130px;
    position: absolute;
    left: 50%;
    top: 60px;
    /*让文本居中*/
    text-align: center;
    display: none;
    z-index: 9999;
}

.sucess h1 {
    font-size: 40px;
    margin-top: 40px;
    color: pink;
}

.results,
span {
    margin-top: 30px;
    color: cyan;
    font-size: 20px;
    font-weight: bold;
}

.return {
    color: orangered;
    margin-top: 10px;
}