What should I aim to include in a Digital Design portfolio? Is HTML/CSS an absolute necessity?

I'm looking to apply for a few digital design positions, but I want to try and really hone my portfolio to be very specific to digital design in particular. My understanding is that digital design is effectively a jack-of-all-trades type position (please correct me if I'm wrong), from graphic design, to animation, to web design. I have background in graphic design, illustration, general programming, and animation, but I'm curious if I should add web design to a list of things to teach myself?

I have a background in game design programming, including making some pretty ambitious video game projects by myself, but I use a drag & drop code method. Is this useful at all towards a digital design portfolio, or are most openings looking for HTML/CSS specifically? Is general programming knowledge useful at all, or would I be better off not including it?

Thank you in advance for any help, and I apologize if this isn't really suited for this subreddit.

Great design resource

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