Hi, I also do have the issue.
Tired two method, one is what you have suggested, instead the code into theme.css
#buddypress .standard-form div.submit input {
color: #000 !important;
}
It does not work.
I have a also come across a post stating about the height under” what-new-option”. Currently it is state 0px, so I change it to 40px first using firebug to try, and it actually appear, so I ask my friend to change it in my theme css(I do not know coding actually), and save the file. It doesn’t reflect again. Now I know it is actually visible, but it wont allows any changes in the less theme css.
