I'm making my own (classic) theme for the first time. After I installed the test XML data, I noticed that some things weren't displayed correctly. For example, H1-H6 are assigned the CSS class .has-large-font-size, but they have no effect. I see in ChromeDevTools that the class attributes have been assigned. But they don't appear in the CSS area. Not even as an empty rule. Setting rules in my style.css doesn't have any other result either. I have the same difficulty when trying to format the page title, which I get from get_title(), using the costumizer. Works for all elements (for changing colors, fonts, etc.), except for the page title.
Would someone be so kind as to help me on the trail? Thank you!