No it looks the same as a regular style, so in theory the code should work.
Maybe it coded in a different way, you could try deleting the img and see what happens, but I think that would cause issues with the page trying to load them.
--------------- Added [DATE]1382485375[/DATE] at [TIME]1382485375[/TIME] ---------------
Lets try this way, add this in the previous code.
Code:
#sidebar_container a.collapse
{
display: none;
}