*{
    margin:0px;
    padding:0px;
}
body{
    background: url("img/background2.jpg") no-repeat ;
    background-position: center 0;
    background-size: cover;
}
#div1{
    border:solid 1px black;
    width:400px;
    height:200px;
    background-color: rgba(44,40,44,.4);
    border-radius: 10px;
    /*设置div块居中*/
    position: absolute;
    left:0; top:0; 
    right:0; 
    bottom: 0; 
    margin: auto; 
}
#divhead p{
    margin-top:30px;
    text-align:center;
    font-size:30px;
    color:white;
}
#divuser,#divpass,#divsub,#divend{
    margin-top:30px;
    text-align:center;
    color:white;
}
div input{
    width:200px;
    border:0px;
    border-bottom:1px solid white;
    background-color:transparent; /* 背景色透明 */
    color:white; 
}
div input:focus{
    height:25px;
}
#divsub input{
    border:1px;
    border-radius: 20px;
    width:100px;
    height:25px;
    background-color: azure;
    color:blueviolet;  
}