CSS unicode trigger image not working with iPad and other Apple product

I’ve replaced the trigger arrows with CSS unicode, which works fine with Chrome, Firefox and IE10 on the PC, however it’s not working with the Safari browser.

It also works with Chrome on my Android phone, but not with the default Android browser.

Also, it does not work at all on the iPad regardless of which browser I use.

Any ideas why??

I know it’s not much bandwidth I’ll save by not using images, but I’ll like to know if it’s possible to make my page extreme lightweight.

Page in question is here (in the 3 small boxes on the front page):

https://www.ads-software.com/plugins/jquery-collapse-o-matic/