I’ve heard it’s harmonious to have the header and body text have similar x-heights. What if your headers have a lower x-height than the body text? Are there any design principles or other issues going against mixing like this?
As I understand it, using a high x-height font in body text will increase legibility. But if your headers have a lower x-height, wouldn’t using a lower x-height font for the body make it less readable?
I read a few related posts here, but they didn’t address my question.
No, you’re not breaking design rules. You can mix and match fonts with various x-heights; what’s important is to look at the page and see if it’s readable.