body {
    font-family: serif;
}

h1 {
    text-align: center;
}

code {
    font-family: monospace;
}

pre {
    font-family: monospace;
    margin-left: 4em;
    margin-right: 4em;
}

.content {
    position: relative;
    margin: 0 auto;
    padding: 0;
    width: 900px;
}

.image, .center {
    text-align: center;
}

@media only screen and (min-width: 768px) and (max-width: 959px) { .main { width: 708px; } }
@media only screen and (min-width: 640px) and (max-width: 767px) { .main { width: 580px; } }
@media only screen and (min-width: 480px) and (max-width: 639px) { .main { width: 420px; } }
@media only screen and (max-width: 479px) { .main { width: 300px; } }