As of 2011
Yes you can, but you will be facing cross-browser compatibility issues:
http://www.quirksmode.org/dom/changess.html
As of 2016
Browser support has improved a lot (every browser is supported, including IE9+).
-
The
insertRule()
method allows dynamic addition of rules to a stylesheet. -
With
deleteRule()
, you can remove existing rules from a stylesheet. -
Rules within a stylesheet can be accessed via the
cssRules
attributes of a stylesheet.