Solved Problem with H2 title on mobile - CSS makes any changes

Hello,
I would like to ask for help. I have my website https://mywandertime.com/ on Wordpress with Divi Theme. I use Child Theme. My problem is that by posts the H2 title on mobile very small is. Even though I did changes in CSS, it didn't make any change (only on desktop).
The only way I could change the size was to change always the post from Wordpress Editor to Divi Builder and there change the formating. But I would prefer to create the posts in Wordpress Editor. Now with last update of Wordpress I cannot change in one post anymore from Wordpress Editor to Divi Builder - I get this error:

TypeError: Cannot read property EditorManager of undefined in TinyMCE in div in ETBuilderTinyMCE in div in div in t in ETBuilderModule in WithDynamicContent (ETBuilderModule) in ForwardRed in t in WithDynamicContent(t)

I also tried to do changes in Theme by typography - when I move the size with 1px, the title suddenly appears bigger. But only in the preview, when I save it, it doesn't make any change. Other titles are alright.

I suppose there might be some mistake in Child Theme which overwrites my changes in CSS. Could anyone help me with this please?

Thank you so much in advance!

 

Now they look fine because I change them in Divi Builder to bigger. But now by new posts I cannot switch back to Divi Builder anymore.
You can have a look e.g. on this post - that is how it is saved from Wordpress Editor: https://mywandertime.com/benelux/venlo/
On desktop it's fine but on mobile H2 is very small.
Thank you

 

Yes it worked! Thank you so much