I saw this feature on one website.

Website viewers can choose their preferance on font size (small, normal, large, extra large) by clicking on a button.
If you click on the image, all the texts on that page gets smaller, larger, and etc. and it does it instantaneously. Meaning, it does not direct you to another page with a different font size but rather it is the same page and all the text size changes size.


Do you happen to know how to accomplish this? One of my site has small font texts and I sometimes have a bit problem reading it myself. I like to give the viewers their choice on font size.