It is used to increase, decrease, reset the font size of your web page with out refreshing the page. I have used a simple Jquery script for this.
First, download and extract it in your extension folder.You should need to add this one line on your view page. It will work on the particular view page you have added.
It can also be used on all pages of your theme. If you need to make it on all pages, go to
/views/layouts/main.php and add this line below the