Animate Elements Continually Using an Infinite Animation Count

HTML-CSS
#1

The bouncing ball looks so real to me. I wonder what process the author took to come up with these values?

top: 249px;
width: 130px;
height: 70px;

Your code so far


<style>

  #ball {
    width: 100px;
    height: 100px;
    margin: 50px auto;
    position: relative;
    border-radius: 50%;
    background: linear-gradient(
      35deg,
      #ccffff,
      #ffcccc
    );
    animation-name: bounce;
    animation-duration: 1s;
    animation-iteration-count: infinite;
  }

  @keyframes bounce{
    0% {
      top: 0px;
    }
    50% {
      top: 249px;
      width: 130px;
      height: 70px;
    }
    100% {
      top: 0px;
    }
  }
</style>
<div id="ball"></div>

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0 Safari/605.1.15.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/applied-visual-design/animate-elements-continually-using-an-infinite-animation-count/

#2

are you asking for help or just doing a ‘review’ on fcc’s challenge??

#3

It’s not a review.

The chosen values in the exercise make me curious and I wonder where these values come from.

#4