As I understood the linked post, you create a new theme folder, create style.css (which links to the default theme) and then any changes you wish to make, are made within the new folder by copying the default files and altering them?
Hmm… think I may be editing the wrong file or something?
I’ve done as you said and created a child theme (which is still activated). I’ve created a new copy of default.css and edited the settings as instructed above, but still no change?
I followed the instructions you gave, but must have done something wrong as the column width didn’t change, but all the widgets it was previously displaying vanished. I had to reinstall BuddyPress from scratch to recover it. Any guesses as to where I went wrong?