There's AmigaGuide (http://code.iamkate.com/articles/amigaguide/ , most screenshots look like they have a dark theme but generally not purple/pink).

Dark theme with purple/pink sounds like the windows 'high contrast dark' theme, which shipped with Windows 95 & 98, and might have shipped with 3.11 / Workgroups as well. In that case, any card-based hypertext system that ran on Workgroups is a possibility. It looks like that includes Authorware (https://en.m.wikipedia.org/wiki/Adobe_Authorware), StorySpace (https://en.m.wikipedia.org/wiki/Storyspace), and probably KMS.

Early versions of HyperTIES ran on DOS: https://www.cs.umd.edu/hcil/hyperties/ ; some HyperTIES images resemble what you describe: https://www.cs.umd.edu/hcil/hyperties/ecs_intro.gif