required properties in bold cannot be distinguished from optional properties
On Mac, with the choose font, the properties in bold cannot be distinguished from the optional one:

When I deactivated the font-family, this is much clearer:

I modified the docson.css stylesheet as follows... required fields become very clear.
.docson .required { font-weight: bold; background-color:#99FFCC; }
.docson .required::after { font-weight:normal; font-family: 'Droid Sans',verdana,helvetica; content: "(required)"; padding: 0 0 0 15px; font-size: 80%; }
Thanks @vaughnteegarden ! That change really makes it obvious now which items are required.
For what it is worth, I have since changed to the below. It is less distracting but still clear, prints better, and the required label is positioned more consistently.
.docson .required { // font-weight: bold; }
.docson .required + .signature-type::after { content: " required"; color: #ff0000; font-size: 100%; padding-left:10px; }