body {
    display: flex;
    flex-direction: column;
    height: 100vh; /* Full height */
    margin: 0;
}
nav, footer {
    flex-shrink: 0; /* Do not allow the nav and footer to grow */
}
main {
    flex-grow: 1; /* Takes up the remaining space */
    overflow: auto; /* Adds scroll to main if content overflows */
}