@import"https://fonts.googleapis.com/css2?family=Roboto&display=swap";html{height:100%}#app{display:grid;margin:20px;height:100vh;grid-template-columns:[col-1-start] 1fr [col-1-end col-2-start] 3fr [col-2-end];grid-template-rows:4.5rem auto 4.5rem;grid-template-areas:"header header" ". main" "footer footer"}header{background:#00f;color:#fff;grid-area:header}main{background:red;color:#fff;grid-area:main}aside{background:green;color:#fff}footer{background:purple;color:#fff;grid-area:footer}