.header {
    width:1000;
    height:100;
    background-color:darkseagreen;
    border-bottom-left-radius:10px;
    border-bottom-right-radius:10px;
    position: fixed
}

.background {
    width:1000;
    height:1000;
    background-color:pink;
    float:left
}

.bottom {
    width:1000;
    height:100;
    background-color:darkseagreen;
    border-bottom-left-radius:10px;
    border-bottom-right-radius:10px;
    float:left
        
}