pre {
    display: block;
    font-family: monospace;
    white-space: pre-wrap;
    margin: 1em 0;
    overflow: auto;
}

#wideimage {
    display: block;
}
#smallimage {
    display: none;
}

@media screen and (max-width: 480px) { 
    #wideimage { display: none }
    #smallimage { display: block; }
}