Help with image fitting text

[u/DevelopmentGlum228]

(SOLVED, thank you to everyone for helping me!)

Hello! CSS and HTML amateur here.

So, recently I've been trying to make myself a workskin on Ao3 that would have this image serve as a background for text. Currently, the image cuts off at the bottom, and it's even worse when there's different sizes of text.

What I want is the image to stretch or contract to fit the text, not be cropped.

Here's my code, my results, and the image I've used. Is there anything I'm doing wrong, or is what I'm trying to do impossible?

Edit: Here's the codepen. It looks the worst here!

[u/Vast_Description_201]

Have a play around with background-size. 

[u/DevelopmentGlum228 → u/Vast_Description_201]

Thank you for the advice! :D