Changing Header colour within customizer causes h2 to resize down

?Can I see the website where this happens, please (with the pop-up enabled)?

https://shop.suttoncoldfieldhypnotherapyclinic.com

If I remove bold from content header everything looks good

Cheers

Okay. You have the following in your theme’s styles:

.b, strong {
    font-size: 16px;
}

It interferes with the styles of our plugin. This can be fixed, but you’ll have to modify your styles by adding this:

.pop-up-cc .b, .pop-up-cc strong {
    font-size: inherit;
}

Let me know if you’re able to do this.

Thank you. That’s the fix

Be well