html,
body {
    margin: 0;
    padding: 0;
    height: 100%;
}

div {
    position: absolute;
    height: 100px;
    width: 100%;
    line-height: 100px;
    font-size: 40px;
    text-align: center;
    top: 50%;
    left: 0;
    transform: translateY(-50%);
}