*{
    cursor:url('../bili.png'),pointer;
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background-size: cover;
    background-repeat: no-repeat;
    background-attachment: fixed;
}

header {
    width:100%;
    height: 80px;
    background-image: repeating-linear-gradient(90deg,aquamarine,aqua);
    box-shadow: rgba(0,0,0,0.7) 2px 5px 6px 10px;
    background-attachment:fixed;
    transition:all .7s;
}

.wrapper {
     display: flex;
     padding-top:20px;
     margin:0 auto;
     width:900px;
 }

 #left {
    float: left;
    width: 350px;
    height: 3000px;
    background-image: url(../pic/c.png);
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-size: 170px;
    background-position: left bottom;
}

#between {
    padding:100px;
    width:944px;
    margin: 0 auto;
    height: 3000px;
    background-color: rgba(256,256,256,0.4);
}

#right {
    float: right;
    width: 350px;
    height: 3000px;
    background-image: url(../pic/d.png);
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-size: 190px;
    background-position: right bottom;
}

#between #picture {
    margin: 0 auto;
    background-color:rgba(0,0,0,0);
    border-radius:10px;
    height: 450px;
    width: 750px;
    background-color: khaki;
    overflow: hidden;
    position: relative;
    border-radius: 10px;
}

#between #categorize{
    margin: 10px auto;
    border-radius: 15px;
    width: 750px;
    height: 100px;
    background-color: bisque;
    display: flex;
}

#categorize div{
    width: 100px;
    border-radius: 10px;
    margin: 20px auto;
    text-align: center;
    line-height: 50px;
}

#categorize div a{
    text-decoration: none;
    font-weight: bold;
    color: blueviolet;
    transition: all .5s;
}
#categorize div a:hover{
    cursor: pointer;
    font-size: 120%;
}

#categorize #math{
    background-color: red;
}

#categorize #web{
    background-color: aquamarine;
}

#categorize #foundationOfProgramme{
    background-color: burlywood;
}

#categorize #knickknacks{
    background-color: rgb(3, 250, 163);
}

#categorize #algorithm{
    background-color: chocolate;
}

#categorize #anime{
    background-color: coral;
}

#categorize #game{
    background-color: cornflowerblue;
}

#categorize #funny{
    background-color: darkcyan;
}

.nav{
    margin-left:400px;
}

.nav ul{
    display:flex;
}

.nav ul li a img{
    height:20px;
    opacity:0.5;
    transition:all 0.4s;
}

.nav ul li a img:hover{
    height:25px;
    opacity:0.9;
}

.nav li {
    margin-top: 30px;
    margin-right: 40px;
    list-style-image:url(../pic/star.png);
}