How to Have Buttons that Resize ALL Text Globally

Hi,

I’m working on a not-for-profit WP for people with disabilities. I’ve been requested to include buttons at the header to allow resizing of text to make using the website easier for them.

I would like to be able to either:

a) Replicate the zoom functionality of browsers (CTRL+’+’,CTRL+’-‘,CTRL+’0’) to resize all the elements, using buttons A- (decrease size), A (default size) and A+ (increase size).

OR

b) Resize all of the text elements on the web page (title, navigation bar, slider text, body text, sidebar text, footer text… everything!), again using buttons A-, A and A+

I have tried using plugins like enlarge text and inoplugs font resizer.

Enlarge text only lets you pick between 3 sizes of text, and with inoplugs, I can’t seem to get it to increase any text in size even though it works in their demo!

Please help. I would love to be able to make the best possible website for this charity. They are doing good work, enabling the severely disabled to learn and use IT. ??

Help to making a plugin work for me would be preferable, but if you can supply code to edit any WordPress files, then I could try my best to follow along. ??

THANK YOU!!! ??

Cheers,
Patricia