*{box-sizing: border-box;}
body{
    background-color: powderblue;
}
a{
    color:blue;
}
a:visited{
    color: red;
}
a:hover{
    color:white;
}
a:active{
    color:black;
}
.content{
    float:center;
    border:solid yellow;
    background-color: powderblue;
    width: 100%;
    height: 600px;
}
.content li{
    float: left;
}
.left{
    float: left;
    position: static;
    border-style:solid;
    border-color:yellow;
    background-color: powderblue;
    height: 600px;
    width: 25%;
}
.left ul{
    list-style-type:none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    width: 100%;
}
.left li a{
    display: block;
    text-align: center;
    padding: 14px 16px;
}
.right{
    float: right;
    position: static;
    border-style:solid;
    border-color: yellow;
    background-color:powderblue;
    height: 600px;
    width: 25%;
}
footer{
    border: solid yellow;
    background-color: powderblue;
    height: 100px;
    width: auto;
}