@import url(https://fonts.googleapis.com/css?family=Yanone+Kaffeesatz:200,300,400);

* {
    box-sizing: border-box;
}

html {
    background: #111 url(https://codepen.io/images/classy_fabric.png);
    color: #fff;
    font-family: 'Yanone Kaffeesatz', sans-serif;
}

main {
    margin: 0 auto;
    max-width: 400px;
}

input[type="number"] {
    border: 0;
    border-radius: 5px;
    font-size: 1.5em;
    padding: 10px;
    width: 100%;
}

input[type="submit"] {
    background: #fff;
    border: 0;
    border-radius: 5px;
    color: #111;
    cursor: pointer;
    font-size: 1.5em;
    padding: 10px;
    width: 100%;
    margin: 20px 0;
}

input[type="submit"]:hover {
    background: #eee;
}