How to use CSS to make a rounding of a different color on a block?

Question

css

I ask you to suggest how it is easier to implement a decorative rounding on the left side of the block.
I think to make two circles, the edges of which will create this look with the help of z-index. But somehow it is cumbersome and difficult to get. Does anyone have a more elegant solution?

Answer 1

Approximately like this - does it fit?