body {
    min-height: 100vh;
    margin: 0;
    position: relative;
}

header {
    min-height: 50px;
}

body::after {
    content: '';
    display: block;
    height: 70px; /* Set same as footer's height */
}

footer {
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 70px;
}