body{
    background: linear-gradient(to top right, silver,gray,black) no-repeat;
}



header{
    text-align: center;
    padding: 15px;
    margin: 10px;
}

.ctverec{
    width: 200px;
    height: 200px;
    background: linear-gradient(cyan, hotpink);
    position: absolute;
    top: 10%;
    left: 46%;
}

.ctverec2{
    width: 200px;
    height: 200px;
    background: radial-gradient(blue, purple, cyan);
    top: 30%;
    left: 46%;
    position: absolute;
}