Source/WebInspectorUI/Tools/CodeMirrorModes/styles.css

body {
    font-family: Arial, sans-serif;
    line-height: 1.5;
    max-width: 64em;
    margin: 2em auto;
    padding: 0 1em;
}

h1 {
    letter-spacing: -3px;
    font-size: 3.23em;
    font-weight: bold;
    margin: 0;
}

.CodeMirror {
    height: auto;
}

.CodeMirror .CodeMirror-lines {
    padding: 4px 0;
}