How to fix a crashed site after modifying Brooklyn theme code for mobile banner resizing?

[Beckenbau]

Hi, we tried to add a code to the theme code, so the banner would resize when opening the shop via mobile version, but now the whole site crashed. 

We did something to the 2 following assets:

•  theme.css.liquid
•  timber.css.liquid

Can u help us to get the correct codes to get a normal working webshop + the correct codes which resizes the banner when opening the shop via mobile version?

Thank you in advance,

Kind Regards,

Beckenbau