I made some changes and the responsive stucture doesn't work on IE

Hello! I made some changes on the theme css and the responsive structure doesn’t work on ie but it works fine on chrome and firefox.

I really tried to find a solution but nothing … can somebody give a help?
Thank you!!

site here

Unfortunately, we are not here to provide free debugging for errors you made when tried to modify theme code. Our suggestion is to reinstall the theme and start over.

I understand! Thank you… maybe i should do the changes step by step.