The issue here is still the same. You’ve added too many buttons to the composer toolbar. That breaks the composer layout on both narrow desktop viewports and on mobile - on any theme.
This theme was designed for the default Discourse layout. If your site requires a lot of extra buttons, then it’s up to you to fix it. I think you’ve already figured out how to do it 
If you need to override the CSS in this theme, then create a theme component with those overrides and add it to your theme.