Am finding it hard to create asticky side bar any help,will be appreciated

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

  **Your code so far**
/* file: index.html */
<!Doctype html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="description" content="Free Web tutorials">

  <meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css"/>

</head>
<body>
  <header class="hero">
    <fieldset class="sidebar">move
    <!--<a href="#">subscribe</a>
    <a href="#">what you should already know</a>
    <a href="#">javascript,java</a>
    <a href="#">hello world</a>
    <a href="#">variables</a>
    <a href="#">Declaring variables</a>
    <a href="#">variable scoop</a>
    <a href="#">Global variables</a>   
    <a href="#">constants</a>
    <a href="#">data type</a>
    <a href="#">if....else statement</a>
    <a href="#">while statement</a>
    <a href="#">functiojdeclaration</a>
    <a href="#">refference</a>-->
    </fieldset>
    <fieldset class="main">
    <section class="section">
      <h1>box 1</h1>
    </div>
    <div class="section">
      <h1>box 3</h1>
    </div>
    <div class="section">
      <h1>box 3</h1>
    </div>
    <div class="section">
      <h1></h1>
    </div>
    <div class="section">
      <h1></h1>
    </div>
    <div class="section">
      <h1></h1>
    </div>
    <div class="section">
      <h1></h1>
    </div>
    <div class="section">
      <h1></h1>
    </div>                
    <div class="section">
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    <div>
      <h1></h1>
    </div>
    </section>
    </fieldset>
    </header>
    <footer>
      footer
    </footer>
</body>
</html>
/* file: styles.css */
*{
border-box:box-sizing;
padding:0;
margin:0;
}
.main{
width:100%;
height:100vh;
right:0;

}

.sidebar{
width:100%;
height:100%;
top:0;
}
.section{
display:inline-block;
padding-top:0;
}
.hero{ 
width:100%;
height:100vh;
display:inline-block; justify-content:space-evenly;
}


  **Your browser information:**

User Agent is: Mozilla/5.0 (Linux; Android 8.1.0; TECNO CF7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Mobile Safari/537.36

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