I'm not sure why my code not passing, any idea?

HTML-CSS
1

Tell us what’s happening:

Your code so far


<style>
  div {
    height: 40px;
    width: 70%;
    background: black;
    margin: 50px auto;
    border-radius: 5px;
    position: relative;
  }

#rect {
  animation-name: rainbow;
  animation-duration: 4s;
}

@keyframes rainbow {
  0% {
    background-color: blue;
    left: 0px;
    
  }
  50% {
    background-color: green;
    left: 25px;
    
  }
  100% {
    background-color: yellow;
    left: -25px;
    
  }
}
</style>

<div id="rect"></div>

Your browser information:

User Agent is: Mozilla/5.0 (X11; CrOS x86_64 10323.67.9) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.209 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/applied-visual-design/create-movement-using-css-animation/

2

As the tutorial said,don’t replace the top property in the editor - the animation should have both vertical and horizontal motion.
Just add a new property to it.