Forum/topic index styling not working properly with my theme

Hey,
I have a couple problems with styling of my forum, which is caused by my theme (I use OceanWP). Is there a way how to fix my issues without changing the theme?

I can’t change a background color of Forum content (odd/even number) nor background of my Forum header/footer. Also my border is not visible on the sides (I have applied dashed line for easy recognition of my border). Next problem is when changing Topic title font/size – when I change it, it changes heading instead (marked yellow in the picture). Otherwise the plugin is wonderful and thank you for work!

The picture