uBlock/src/css/dyna-rules.css

div > p:first-child {
    margin-top: 0;
    }
div > p:last-child {
    margin-bottom: 0;
    }
#rulesEditor {
    font-size: small;
    width: 48em;
    height: 40em;
    white-space: pre;
    text-align: left;
    }
code {
    background-color: #eee;
    font: 11px monospace;
    padding: 2px 4px;
}