Please i need the help to this steps

Tell us what’s happening:
Describe your issue in detail here.

  **Your code so far**
/* file: index.html */
<!DOCTYPE html>
<html>    
<head>
  <title>City Skyline</title>
  <link href="styles.css" rel="stylesheet" type="text/css" />   
</head>

<body>
  <div class="background-buildings">
    <div></div>
    <div></div>
    <div class="bb1">
      <div class="bb1a"></div>
      <div class="bb1b"></div>
      <div class="bb1c"></div>
      <div class="bb1d"></div>
    </div>
    <div class="bb2"></div>
    <div class="bb3"></div>
    <div></div>
    <div class="bb4"></div>
    <div></div>
    <div></div>
  </div>
</body>
</html>
/* file: styles.css */
* {
border: 1px solid black;
box-sizing: border-box;
}

body {
height: 100vh;
margin: 0;
overflow: hidden;
}

.background-buildings {
width: 100%;
height: 100%;
display: flex;
align-items: flex-end;
justify-content: space-evenly;
}
.bb1 {
width: 10%;
height: 70%;
display: flex;
flex-direction: column;
align-items: center;
--building-color1: #aa80ff;
}

.bb1a {
width: 70%;
height: 10%;
background-color: var(--building-color1);
}

.bb1b {
width: 80%;
height: 10%;
background-color: var(--building-color1);
}

.bb1c {
width: 90%;
height: 10%;
background-color: var(--building-color1);
}

.bb1d {
width: 100%;
height: 70%;
background-color: var(--building-color1);
}

.bb2 {
width: 10%;
height: 50%;
--building-color2: #66cc99;
background-color: var(--building-color2);
}


.bb3 {
width: 10%;
height: 55%;
}

.bb4 {
width: 11%;
height: 58%;
}
  
  **Your browser information:**

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Safari/537.36

Challenge: Step 22

Link to the challenge: