When redesigning my website to use Bootstrap, I ran into a problem. The navbar (meny) did not render correctly in Internet Explorer 9, despite looking perfect in Firefox and Internet Explorer 10. There are several discussions about this problem on StackOverflow and other forums, and the solution is simply to add <!DOCTYPE HTML> on the first line of the HTML code.
However, IBM Domino automatically adds a different doctype string, and there is no database or form property to change/set the correct value. But there is actually a way, and it is not very complicated.
This way to modify the HTML generated is documented in the online help. It was added in Domino 8.
A little while ago I did a post on this too, with info on how to set the correct DOCTYPE for other design elements too: http://blog.defrog.nl/2011/12/how-to-set-correct-doctype.html
I missed that one, but great info!