Trouble with Fallback value to a CSS variable

Hi have an issue with this, I have as you are suggesting and still the code is not completing. Can you spot anything wrong with my code, as I have tried this and have not been able to rectify the problem.?

<style>
  .penguin {
    --penguin-skin: gray;
    position: relative;
    margin: auto;
    display: block;
    margin-top: 5%;
    width: 300px;
    height: 300px;
  }
  
  .penguin-top {
    top: 10%;
    left: 25%;
    
    /* change code below */
    background: var(--penguin-skin black);
    /* change code above */
    
    width: 50%;
    height: 45%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .penguin-bottom {
    top: 40%;
    left: 23.5%;
    
    /* change code below */
    background: var(--penguin-skin black);
    /* change code above */
    
    width: 53%;
    height: 45%;
    border-radius: 70% 70% 100% 100%;
  }
  
  .right-hand {
    top: 0%;
    left: -5%;
    
    /* change code below */
    background: var(--penguin-skin black);
    /* change code above */
    
    width: 30%;
    height: 60%;
    border-radius: 30% 30% 120% 30%;
    transform: rotate(45deg);
    z-index: -1;
  }
  
  .left-hand {
    top: 0%;
    left: 75%;
    
    /* change code below */
    background: black;
    /* change code above */
    
    width: 30%;
    height: 60%;
    border-radius: 30% 30% 30% 120%;
    transform: rotate(-45deg);
    z-index: -1;
  }
  
  .right-cheek {
    top: 15%;
    left: 35%;
    background: white;
    width: 60%;
    height: 70%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .left-cheek {
    top: 15%;
    left: 5%;
    background: white;
    width: 60%;
    height: 70%;
    border-radius: 70% 70% 60% 60%;
  }
  
  .belly {
    top: 60%;
    left: 2.5%;
    background: white;
    width: 95%;
    height: 100%;
    border-radius: 120% 120% 100% 100%;
  }
  
  .right-feet {
    top: 85%;
    left: 60%;
    background: orange;
    width: 15%;
    height: 30%;
    border-radius: 50% 50% 50% 50%;
    transform: rotate(-80deg);
    z-index: -2222;  
  }
  
  .left-feet {
    top: 85%;
    left: 25%;
    background: orange;
    width: 15%;
    height: 30%;
    border-radius: 50% 50% 50% 50%;
    transform: rotate(80deg);
    z-index: -2222;  
  }
  
  .right-eye {
    top: 45%;
    left: 60%;
    background: black;
    width: 15%;
    height: 17%;
    border-radius: 50%; 
  }
  
  .left-eye {
    top: 45%;
    left: 25%;
    background: black;
    width: 15%;
    height: 17%;
    border-radius: 50%;
  }
  
  .sparkle {
    top: 25%;
    left: 15%;
    background: white;
    width: 35%;
    height: 35%;
    border-radius: 50%;
  }
  
  .blush-right {
    top: 65%;
    left: 15%;
    background: pink;
    width: 15%;
    height: 10%;
    border-radius: 50%;
  }
  
  .blush-left {
    top: 65%;
    left: 70%;
    background: pink;
    width: 15%;
    height: 10%;
    border-radius: 50%;
  }
  
  .beak-top {
    top: 60%;
    left: 40%;
    background: orange;
    width: 20%;
    height: 10%;
    border-radius: 50%;
  }
  
  .beak-bottom {
    top: 65%;
    left: 42%;
    background: orange;
    width: 16%;
    height: 10%;
    border-radius: 50%;
  }
  
  body {
    background:#c6faf1;
  }
  
  .penguin * {
    position: absolute;
  }
</style>
<div class="penguin">
  <div class="penguin-bottom">
    <div class="right-hand"></div>
    <div class="left-hand"></div>
    <div class="right-feet"></div>
    <div class="left-feet"></div>
  </div>
  <div class="penguin-top">
    <div class="right-cheek"></div>
    <div class="left-cheek"></div>
    <div class="belly"></div>
    <div class="right-eye">
      <div class="sparkle"></div>
    </div>
    <div class="left-eye">
      <div class="sparkle"></div>
    </div>
    <div class="blush-right"></div>
    <div class="blush-left"></div>
    <div class="beak-top"></div>
    <div class="beak-bottom"></div>
  </div>
</div>

Use three backticks before and after your code , it will be difficult to give any suggestion from this raw code text.
Backtick key is present before the number 1 key in keyboard

I knew that after it posted like that thanks @Sujith3021 , as I could not delete it after posting. Even doing that my code is not working before posting.

You should have three backticks at the start of your code too or click this symbol </> in the message box and paste the code between those

I corrected the code by removing the color element, then it passed. Thanks everyone for their help.