The most semantic way of making this container

Question

I want to make the following shape using divs and border radius, with fall back to square corners for old browsers. No images please.

I am having a bit of trouble ma

Answer 1

As many suggested before, dark div with white div inside and border-radius on bottom-left corner. Example here.

The code is rough and should be rewritten, but it works. And you should synchronize div background color with page color.