How to draw a semicircle in CSS?

Question

css

More precisely 200px wide from its full 500px. What properties and how to set

Answer 1

jsfiddle.net/ffvv40wr/1
Can be implemented with both border-radius and SVG.
Of course, both options are better to use in the background, otherwise you will have to set absolute positioning (or fixed, which is even worse).
Using SVG has the advantage that by setting only the height and width, you don't have to worry about the rounding radius (as you can see in the 3rd example, when you have to change the width for :before).

Answer 2

or border radius