body{background-color:white;} h1{color:red;font-size:70px;text-align:center} h2{color:blue;font-size:40px;text-align:center} body{width: expression ( document.body.clientWidth < 1000 ? "1000px" : "auto"); min-width: 1000px;} .under{ min-height: 100vh; position: relative; padding-bottom: 120px; box-sizing: border-box; } footer{ width: 100%; text-align: center; padding: 30px 0; position: absolute; bottom: 0; }