To add to what Susan said, Outlook in general is very picky when it comes to emails. Unfortunately, there is a lot of css and code formatting that it doesn’t support so it will just ignore it in the email completely.
If you are a little bit comfortable with HTML (or can find someone who is), one thing to try is copying the source code from the email, pasting it here (https://inliner.cm/), clicking ‘Make It Inline’, and pasting it back into WineDirect. (Inlining moves the placement of the CSS styles already present in your email directly into the HTML code.) This will help the picky email clients read it better. Any CSS that isn’t supported by Outlook won’t be fixed, but it should definitely help.