Hello,
We would recommend you:
1) Use image as the background for the div and without text
2) Add text inside div with the custom class as we did http://prntscr.com/nazrkh
3) We have added custom code for the desktop and mobile versions to make the text size fix device, for example http://prntscr.com/nazsyt and http://prntscr.com/nazt70
Check and let me know if it suits your needs.
Regards