You mean the ajax search pro custom css on the Theme Options -> Custom CSS section?
I just logged in and tried a random CSS, but it did save for me for some reason. I suspect it might be either maybe a browser plugin or an unknown bug yet.
Can you try:
– After copy/pasting the custom CSS, enter one more character and then just delete it. It might trigger the value change event, which I suspect is somehow not working correctly.
– ..if that doesn’t work, try without browser plugins enabled
– ..if none of this work, maybe a different browser? (preferably google chrome or mozilla firefox)