/* layout-basic.css */
div.main::before {
    content: "";
    display: block;
    height: 100vh;
    margin-top: -200px;
    overflow: hidden;
    width: 100%;
}
div.main {
    min-height: 100vh;
}
div.main > section {
    background: #fff;
    box-sizing: border-box;
    display: block;
    padding: 20px;
}
div.main > section + section {
    margin-top: 20px;
}
footer.main {
    min-height: calc(100vh + 20px);
}

@media (min-width: 768px) {
    div.main::before {
	height: 25vh;
	margin-top: 0;
    }
    div.main {
	min-height: 75vh;
    }
    div.main > section + section {
	margin-top: 50px;
    }
    footer.main {
	min-height: 25vh;
    }
}