Its probably an issue due to using pixels for height/position parameters, its better to avoid using px and use the column system instead. If not, the html will appear shifted or completely messed up depending on the device size.
I spent the last couple of days on circlejourney adapting a screenshot of a pokemon box into a layout for my characters, but when I copied it into a toyhouse page (with WYSIWYG OFF) it entirely breaks.
Left is how it looks in circlejourney, right is how it looks on TH.
I've realised that I might not be able to use google fonts without premium, but that shouldn't break as much as is broken, as tested on the circlejourney version. Also, I only used inline CSS so that shouldn't be an issue.
Here's a pastebin of the code if needed: https://pastebin.com/fvP7WwBx
aspect-ratio is not whitelisted on Toyhouse, meaning you can't use that specific property.
Your best/ only option is to set the specific width and/ or height to your elements and then use the appropriate background-size or find alternative ways to imitate the look of the graphics without having to rely on background-images/ graphics (ex. using borders, box-shadows, border-image, etc).