img { max-width: 100%; height: auto; }

@media (min-width: 320px) and (max-width: 640px) {
    body {
	font-size: 16px;
    }
    .small {
	font-size: 12px; /* 75% of the baseline */
    }
    .large {
	font-size: 20px; /* 125% of the baseline */
    }
    ol li {
/* might be able to go lower, but this seems like a nice mobile default */
	padding: 6px;
    }
}