Possible to support rendering MHTML files?

If I save a page from Vivaldi as a single file, it saves a .mhtml file, which is a MIME-encapsulated HTML file with all the CSS, fonts, images etc in the file as MIME attachments. Essentially, the same as a .webarchive, but with the major advantage that anything that has been blocked by a content blocker does not get included in the archive — exactly what I want!

However, DT3 does not render these correctly:

It appears to be treating it as a plain HTML file, and getting confused by the MIME boundary markers, causing them to be rendered as text — and all the CSS, images etc get dumped out as text as well:

Please could we have support for properly displaying this file format? With Safari 13’s removal of non-App Store extensions, many of the extensions I use are no longer available, meaning I am unable to continue using it and must switch to Vivaldi.

Thanks!

Could you please send such a file to cgrunenberg - at - devon-technologies.com? Thanks.

Thanks — sent!