custom css not working in style.css

Hello

I have a fresh install of wordpress, with elementor pro and hello with hello child theme.
When i add any custom css to the style.css it does'nt change anything on the website, but if i add it to a elementor css custom box then it works. I've tried turning off the few plugins i have on, off and nothing changes. Also no caching plugin is running.

is there something i need to do to make the style.css work? It appears in wordpress file editor but ive tried adding via that method and just editing the file and uploading via ftp, but no difference.

Thanks