Hi, Yuval.
Anytime you start using our Themer’s Guide, we can’t really advise what CSS selectors you’d need to use because you might have altered them.
Therefore, after you have your template how you want it, please try a plugin like SiteOrigin CSS because it helps you visually build CSS selectors via its Inspector and Visual Editor, which I’d guess would be helpful to you.
If you’re not a CSS expert, Jetpack’s Custom Design reference may prove helpful.
Please let me know how it goes for you. If you don’t find joy with this, please send me a link to view this on your site and also send an annotated screenshot of what changes you’d like to see.