body {
    margin: auto;
    width: 500px;
    background-color: oldlace;
}
h1 {
    text-align: center;
    font-family: sans-serif;
}
div {
    position: absolute;
    width: 400px;
    height: 400px;
}
.wrapper {
    position: relative;
    width: 100%;
    height: 500px;
}
.alpha {
    background-color: mediumspringgreen;
    left: 50px;
    top: 50px;
}
.beta {
    background-color: blueviolet;
    left: 50px;
    top: 50px;
}