body {
    margin: 0 auto;
    overflow: hidden;
}

.header {
    margin: 0 auto;
    width: 100%;
    height: 640px;
    /*background-color: #000;*/
    /*position: relative;*/
}

    .header canvas {
        width: 100%;
        height: auto /*默认全屏显示 可自己设置高度640px*/;
        display: inline-block;
        vertical-align: baseline;
        /*position:absolute;*/
        z-index: -1;
    }

.audio {
    width: 45px;
    position: fixed;
    top: 65px;
    left: 94%;
    z-index: 100;
    filter: alpha(opacity=30);
    -moz-opacity: 0.3;
    -khtml-opacity: 0.3;
    opacity: 0.3;
}

.header .nav {
    display: flex;
    justify-content: center;
    align-items: center;
    height:100%;
    z-index: 30;
    background: rgba(0,0,0,0.6);
    padding: 20px 35px;
}

    .header .nav a.gv {
        text-decoration: none;
        background: url(../images/Nebula3.png) repeat 0px 0px;
        width: 130px;
        height: 43px;
        display: block;
        text-align: center;
        line-height: 43px;
        cursor: pointer;
        float: left;
        margin: 8px 2px 8px 2px;
        font: 18px/43px 'microsoft yahei';
        color: #00fff3;
        box-shadow: 0 0 18px #00ffe7;
    }

        .header .nav a.gv span {
            display: none;
        }

        .header .nav a.gv:hover {
            background: url(../images/Nebula3.png) repeat 0px -43px;
            color: #8efffa;
            -webkit-box-shadow: 0 0 10px #ffffff;
            transition-duration: 0.5s;
        }

.header .topcn {
    width: 980px;
    top: 200px;
    left: 50%;
    margin-left: -490px;
    position: absolute;
    z-index: 20;
}