* {
    margin: 0;
    padding: 0;
}

body {
    display: flex;
    flex-wrap: wrap;
    flex-direction: row;
}

header {
    height: 20vh;
    flex: 1 1 100%;
    background-color: lightgreen;
}

nav {
    height: 70vh;
    flex: 1 1 15%;
    background-color: yellow;
}

main {
    height: 70vh;
    flex: 1 1 70%;
    background-color: rosybrown;
}

aside {
    height: 70vh;
    flex: 1 1 15%;
    background-color: lemonchiffon;
}

footer {
    height: 10vh;
    flex: 1 1 100%;
    background-color: red;
}