When I made the upper88-wordclod web component everything worked fine when I had hard-coded sizes in the beginning. The library worked well and gave the ouput I expected (well, actually a bit better, it's an awesome library).
But when I switched to a size set with CSS it stopped working. After some debugging I realized that the element had no size yet. When attachedCallback(which is the place where you would render your element for the first time) is called, the element has no size set yet, so if your code (or a library you might use) relies on getting the height or width of the element ity won't work.