CSS3DRenderer: I don’t think the elements need preserve-3d.

examples/js/renderers/CSS3DRenderer.js

@@ -9,10 +9,6 @@ THREE.CSS3DObject = function ( element ) {
 
 	this.element = element;
 	this.element.style.position = 'absolute';
-	this.element.style.WebkitTransformStyle = 'preserve-3d';
-	this.element.style.MozTransformStyle = 'preserve-3d';
-	this.element.style.oTransformStyle = 'preserve-3d';
-	this.element.style.transformStyle = 'preserve-3d';
 
 	this.addEventListener( 'removed', function ( event ) {