WP PageNavi Styling Pagination Elements – with 2 and 3 digits bg img

I have this code in my functions.php:

https://pastebin.com/d0nCBVAm

And I need to know what part of this do I need to use in my CSS to set a background image for pages 10-99 and 100-999 (set wider background image to contain the numbers)

Here is my CSS:

https://pastebin.com/L54J53k8

And here is a current Screen Shot:

https://i43.tinypic.com/21vtrl.png
<img stc=”https://i43.tinypic.com/21vtrl.png”/&gt;

10 and 100 will need a new CSS class
And How would I also do this for the NEXT and Previous Buttons?

Thanks