> feature compatibility should be determined on a case-by-case basis by simply attempting to detect/use the specific feature That's a fine goal. When writing

> feature compatibility should be determined on a case-by-case basis by simply attempting to detect/use the specific feature That's a fine goal. When writing my own component framework for browsers, detection was regularly impossible and I had to depend on browser sniffing. Modernizr code has some very smart hacks (sometimes very dirty hacks) to detect features - a large amount of work for them to develop trustworthy detection code. And detection was usually via side-effects. My educated guess is that feature detection for Web3D is not simple. A quick google and I didn't find an obvious Web3D feature detection library. Here's part of the detection code for :checked support in Modernizr: Modernizr.addTest('checked', function(){ return Modernizr.testStyles('#modernizr input {width:100px} #modernizr :checked {width:200px;display:block}', function(elem, rule){