styles and scripts are enqueued in a function run from the bp-default functions.php file
Mid way down this page explins the workings:
You can either call the function yourself in your child themes function.php file – which will override the running of the bp version – and then simply declare the files you want omitting the ones you don’t or you can go another route and de-register the responsive stylesheet.
The example I linked to above doesn’t actually show the responsive sheet as being declared so was probably written before that stylesheet was included so you may get away with copy pasting the function to your functions.php file.
However I would think rather than remove ‘responsive’ a better course of action is to id where the issue is happening first, as collapsing the sidebar doesn’t sound right and I wouldn’t have thought the responsive sheet would have done this.
Thanks for the thorough response. I’m not sure if I did it right but I pasted the function into my function.php and that got rid of all my styles from my child theme style sheet which confused me.
Collapsing is the wrong word. What happens is it shoves my sidebar underneath the content and since I’m making a mobile version of my site I don’t need that to happen and it takes an absolute positioned element in the sidebar and overlaps it to the top of the content.
Post what you did so we can work with you from there.