With Domino 8.5 web applications, there is a setting that lets you enable "Enhanced HTML generation". This generates markup closer to the HTML specifications.
Another nice thing about it is that some of the design elements (views, actionbar, outline, etc.) gets a class-attribute on its generated HTML.
For instance, the action bar table gets a domino-actionbar class. No more hacks needed to style the action bar..
I haven't found a complete documentation of all the generated classes. This is about the only documentation I found on the subject. I wish IBM would get a bigger team working on documentation. One of the reasons features aren't used is lack of documentation.