What is this UI style called?

[ayvacs]

Hey! This isn't a question specifically aimed at ImHex, but I've noticed a ton of programs use this specific UI style (just the general design of the popups, the blue/gray colour scheme, and the font)

I've been wondering for a while if this style is just a coincidence or if it's the result of using a certain UI library or something similar?

Thanks!

Here's an image of another program that uses the same style for popups:

[glpnk]

This is Dear ImGui. Check this list for other projects using it.