What is the purpose of position:absolute in this challenge?

I currently learningCSS to create complex shapes
In this challenge, We use position:absolute to create a heart-shaped object. However, I did not understand what is the importance of position:absolute and how that happened if we applied
theborder-radius: 50%; we should use position:absolute.

My best advice is to make each heart, heart:before & heart:after different background colors and experiment with the values to see how it affects the image.