body {
    font-family: Arial, sans-serif;
    max-width: 640px;
    margin: 3em auto;
    padding: 0 1em;
    color: #222;
}
h1 {
    font-size: 1.4em;
}
form {
    margin-top: 1.5em;
}
label {
    display: block;
    margin-bottom: 0.3em;
}
input[type="text"] {
    padding: 0.4em;
    width: 100%;
    max-width: 250px;
    margin-bottom: 1em;
    box-sizing: border-box;
}
button {
    padding: 0.5em 1.2em;
    cursor: pointer;
}