.header {
    grid-area: header;
}

.main {
    grid-area: main;
}

.sidebar {
    grid-area: sidebar;
}

.footer {
    grid-area: footer;
}

.container {
    display: grid;
    grid-template-columns: 33% 33% 33%;
    grid-template-rows: auto;
    grid-template-areas:
        "header header header"
        "main main sidebar"
        "footer footer footer";
    column-gap: 10px;
    row-gap: 15px;
}

.menu {
    display: flex;
}

.menu-item {
    list-style: none;
    padding: 20px 20px;
}