<style>
#container {
    position: absolute;
    width: 500px;
    height: 400px;
    border: 1px solid black;
}
#red {
    position: absolute;
    left: 20px;
    top: 20px;
    background: red;
    width: 100px;
    height: 100px;
    border: 10px solid gray;
}
#green {
    position: absolute;
    right: 20px;
    top: 20px;
    background: green;
    width: 100px;
    height: 100px;
    margin: 50px;
}
#blue {
    position: absolute;
    left: 20px;
    bottom: 20px;
    background: blue;
    width: 100px;
    height: 100px;
}
#yellow {
    position: absolute;
    right: 20px;
    bottom: 20px;
    background: yellow;
    width: 100px;
    height: 100px;
}
</style>
<div id=container>
    <div id=red></div>
    <div id=green></div>
    <div id=blue></div>
    <div id=yellow></div>
</div>