* {
    box-sizing: border-box;
    outline: 0
}

a {
    color: inherit
}

body {
    background-color: #1e1e1e;
    color: #fff;
    cursor: default;
    font-family: Helvetica,sans-serif;
    font-size: 16px;
    margin: 0;
    -webkit-tap-highlight-color: transparent
    
}

header {
    background-color: rgba(255,255,255,.1);
    padding: 10px 15px;
    -webkit-user-select: none;
    user-select: none
}

h1 {
    margin: 15px 0
}

main {
    display: block;
    margin: 15px
}

.bg-img {
    background-attachment: fixed;
    background-image: url("https://hdqwalls.com/wallpapers/blue-dunes.jpg");
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    -webkit-filter: blur(10px);
    filter: blur(10px);
    height: 100%;
    left: 0;
    opacity: .5;
    position: fixed;
    top: 0;
    transform: scale(1.1);
    width: 100%;
    z-index: -1
}

ul {
    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
}

li {
    float: left;
}

a:link,a:visited {
    display: block;
    width: 120px;
    font-weight: bold;
    color: #fff;
    text-align: center;
    padding: 15px;
    text-decoration: none;
    text-transform: uppercase;
}

a:hover,a:active {
    background-color: #000;
}

body {
    background: url("https://hdqwalls.com/wallpapers/blue-dunes.jpg") no-repeat center center fixed;
                /*兼容浏览器版本*/
    -webkit-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}