.container {
    height: 100%;
    display: grid;
    grid-gap: 3px;
    grid-template-columns: repeat(12, 1fr);
    grid-template-rows: 40px auto 40px;
}

.header {
    grid-column: 1 / -1;
}

.menu {}

.content {
    grid-column: 2 / -1;
}

.footer {
    grid-column: 1 / -1;
}