After looking through the JS spine source and from what I know about HTML/CSS I would say that it's possible to render using CSS3: http://www.w3schools.com/css/css3_intro.asp

Meshes are going to be harder to render. I'm not seeing anyway to render the triangles/mesh data in CSS3. I have found textured quads rendered with perspective: http://www.edankwan.com/lab/css3dEarth but unless you can degenerate the quad into a triangle I'm coming up short...

You don't need mesh support. Just don't use any meshes in your animations.

Aye, a number of Spine runtimes can't render meshes: Flash (without Starling), Corona, SpriteKit, etc. You can still do a lot without meshes, eg:
https://github.com/EsotericSoftware/spine-superspineboy

I know you said no Canvas, but there is a turbulenz example:
http://esotericsoftware.com/files/runti ... z/example/
This (somewhat dated) PR has a Canvas only example:
https://github.com/EsotericSoftware/spi ... s/pull/123
Other than that, I don't have example code I can show. You just need to extend spine-js to do the rendering using whatever you like. It's a bit tricky to get things positioned in exactly the right place, and your skeleton will generally look FUBAR until it works perfectly.

Checking to see if anyone knows of a HTML DOM-only (no Canvas, no WebGL) runtime for Spine.

There is no such thing at the moment I'm afraid. If you want HTML DOM-only to compose it with the rest of your website, you could actually still use the canvas renderer. As long as you clear the canvas to be fully transparent, it should be easy to composite with the rest of your DOM.

What is your use case for a DOM renderer?

I'd read conflicting reports on "sprite" rendering performance DOM vs. canvas. Also, a morbid pursuit of maximal browser support. It's likely that canvas is sufficient, but I wanted to know what the options were. Even Internet Explorer 9 supports canvas. Thanks for the reply!

badlogic,
you stated: "As long as you clear the canvas to be fully transparent"

how can i make the spineboy canvas example have a transparent background?

That's done with plain old browser magic and not spine-canvas specific. Here's a couple of ways, ymmv as with all browser tech. https://stackoverflow.com/questions/4815166/how-do-i-make-a-transparent-canvas-in-html5

actually, solution is just this:

this.gl.clearColor(0, 0, 0, 0);