Edit in JSFiddle

body {
    margin:0;
}
div {
    float:left;
    border: 1px solid black;
    padding:10px;
    width:50%;
    box-sizing:border-box;
    height:100vh;
}
.c1 {
    background-color: blue;
}
.c2 {
    background-color: lightblue;
}

<div class="c1">Column 1</div>
<div class="c2">Column 2</div>