No problem – because your heading is not H1.
Therefore the rule does not apply to it.
Now I can see it since you’ve provided a link to your store
Look at the screenshot below and check yours:
It may be set as H1 under “Typography” but this settings is about the look, not function.
In fact, that’s where you can change the font size (instead of using CSS).
I bet you have “Paragraph” where I have “H1”.
This is where you actually set what tag is used for your heading. It is “H1” by default, but you can easily change it to whatever available in drop-down.
Horizon is very (sometimes overly) flexible. And sometimes not obvious.
But anyway – Customizer (‘edit theme’) is your main tool in setting up your online store.
That’s what I meant in my second post in this thread. no offence.
