Your feedback about the need for an Inventor dark theme has led to this pre-release theme being included in Inventor 2021.

Want to try it out? In Inventor, go to Tools Application Options panel Colors tab. In the UI Theme section, click the dropdown list and select Dark (pre-release).

What's included in the pre-release theme?

• Rearranged Colors tab dialog because theme selection affects the Color Schemes
• Easily switch between Dark and Light themes
• A new "Dark" color scheme with complementary color values
• The color scheme Light was formerly named Light Theme

For more information see Dark (pre-release) Details.