Sort of... You can apply style rules to web pages that specify the heading size in proportion to the

Sort of... You can apply style rules to web pages that specify the heading size in proportion to the size of ordinary text, and that should allow them to zoom proportionately.

By default, these values are:

ordinary text: 1em = 16 pixels

h1: 2em, or 2 x 16 pixels = 32 pixels

h2: 1.5em, or 1.5 x 16 pixels = 24 pixels

h3: 1.17em, or 1.17 x 16 pixels = 18.7 pixels

To re-proportion the headings, you could try this set of rules:

h1 {font-size:1.4em !important;} h2 {font-size:1.25em !important;} h3 {font-size:1.1em !important;}

To apply that to pages, you have two choices:

(1) userContent.css file

This is a file that does not ship with Firefox but can be created in your active settings folder (AKA Firefox profile folder). It's efficient in that it doesn't require an add-on, but only is read at startup, so fine-tuning rules is a chore.

(2) Stylish extension

This add-on allows you to create rules that you can edit and preview instantly so you can see whether you like the result.

There are numerous threads describing how to use these two tools, and for Stylish, the userstyles.org site contains many examples of rules you can try out.

Hope this helps.