*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body{
    font-size: 16px;
    color:black;
}
a{
    text-decoration: none;
}
.nav li a:hover{
    border-bottom: black;
 }
image{
    vertical-align: middle;
}

/* 单伪元素消除法消除浮动影响 */

.clearfix::after{
    content: "";
    display: block;
    clear: both;
}

li{
    list-style: none;
}