#header {
    margin-left: auto;
    margin-right: auto;
    max-width: 768px;
}

#content {
    margin-left: auto;
    margin-right: auto;
    padding-left: 1em;
    padding-right: 1em;
    padding-bottom: 100px;
    max-width: 768px;
    line-height: 150%;
}

.alert{
    background-color: #e60f13; 
}

.highlight{
    background: #ffff99;
}

pre {
    margin-left: 2em;
}