Headings gets smaller when using Toggle font size

You’ll need to supply custom styles to be triggered by the font size toggle.

There are many, many ways of defining font sizes, and one of the unfortunate results of that is that I can’t really design a stylesheet that will always have the right effect; there are too many variables.

You can add custom styles to your theme stylesheet under the .fontsize class, attached to the body element, and alter how the toggle changes your headings.

An example might be:

.fontsize h2 { font-size: 2em!important; }

But that’s just a generic example.