[Solved] CSS issues on mobile (PS 1.6)

[NSN]

I have 2 shops running on PS 1.6.2.16, both with modified standard theme. One shop is working as expected, but the other is having issues with CSS on mobiles.

When Smart cache for CSS is disabled, the CSS is loaded to a usable point, but the footer is broken and the shopping cart does also not show proper design (item list and shipping block).
When Smart cache for CSS is enabled, the CSS is not loaded at all.

Any ideas where I can solve this issue? Trying long time but could not find it.

SOLVED: Missed a single bracket in global.css

Edited October 12, 2023 by NSN (see edit history)