Found this horizontal bar with multiple-colored rectangles in notion, how could we recreate it?

Hi, I found this notion template in reddit, and saw this colored bar with multiple rectangles:

I think it could be useful as a line separator (like the --- line) or simply for aesthetic reasons. I think this could be achieved with css, but it goes well beyond my beginner css capabilities.

Link to the original reddit post:

Thanks in advance for any help.