Has the css or code for the burger icon changed in 3x ?

Has the css or code for the burger icon / button changed drastically from Elgg 2x to 3x ? I cannot find any documentation in the docs. In 3x, most of the times the menu will not open or close but there is no definite steps I can describe so that you can test this. You can repeatedly click and see. Sometimes this happen with just one click also.
This problem is not with Elgg 2x.