Board Thread:Support Requests - Getting Technical/@comment-40192222-20190718083705/@comment-168424-20190719160600

Not sure this has anything specifically to do with FANDOM.

But to answer your question, px are definitely better for precise image scaling. Em's and en's were designed for font and text usage and they often don't even represent what they are canonically supposed to be a measurement of: specific m or n character width in a particular font. CSS changed this because it was too complicated.