Can't pass the #navbar test in the Portfolio project

Hello! I couldn’t pass the #navbar test in my portfolio project:
Error message: Your “#navbar” element should always be at the top of the viewport.
Any help will be appreciated!
Your code so far

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 <!DOCTYPE html>
<html>
<head>
  <title>Portfolio Web Page</title>
  <meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no">
  <link rel="stylesheet" href="styles.css">
</head>
<body>
  <header id="navbar" class="nav">
    <ul class="nav-list">
      <li><a class="active" href="#welcome-section">About</a></li>
      <li><a href="#projects">Projects</a></li>
      <li><a href="#contact">Contact</a></li>
   </ul>
  </header> 
 
<section id="welcome-section">
    <h1>Hello! I'm Lu Chi.</h1>
    <p> a front-end web developer</p>
</section>

<section id="projects" class="projects-section">
  <h2 class="projects-section-header">These are some of my projects</h2>
  
  <div class="projects-grid">
    <a href="https://codepen.io/luluchi/full/abOgpyq" id="profile-link" target="_blank" class="project-tile">
      <img class="project-image" src="https://i.postimg.cc/xCLKz0Vr/Tribute-Page.png" alt="Bruce Lee"/>
      <div class="text-block">
          <h3>Tribute Page</h3>
      </div>
    </a>
      
    <a href="https://codepen.io/luluchi/full/poJMEZL" id="profile-link" target="_blank" class="project-tile">
     <img class="project-image" src="https://i.postimg.cc/C5mnG5v2/Product-Landing-Page.png" alt="product landing page"/>
     <div class="text-block">
          <h3>Product Page</h3>
      </div>
    </a>

   <a href="https://codepen.io/luluchi/full/BaooNNX" id="profile-link" target="_blank" class="project-tile">
     <img class="project-image" src="https://i.postimg.cc/sxNDfhH3/Technical-Document-Page.png" alt="technical document page"/>
     <div class="text-block">
          <h3>Technical Document</h3>
      </div>
    </a>

   <a href="https://codepen.io/luluchi/full/LYVKQGZ" id="profile-link" target="_blank" class="project-tile">
     <img class="project-image" src="https://i.postimg.cc/nznL3ZQf/Survey-Page.png" alt="survey page"/>
     <div class="text-block">
          <h3>Survey</h3>
      </div>
    </a>
  </div>
</section>

<section id="contact" class="contact-section">
  <div class="contact-section-header">
    <h2>Let's work together...</h2>
    <p>How do you take your coffee?</p>
  </div>
  
  <div class="contact-links">
    <a href="https://www.linkedin.com/in/lu-yang-a6b2a5124/"
      target="_blank" class="btn contact-details"><img src="https://i.postimg.cc/NFgqjpRv/16090541531530099327-128.png"class="contact_icon"/></a>
      
    <a href="mailto:example@example.com" class="btn contact-details" target="_blank"
      ><img src="https://i.postimg.cc/rmjZQcR7/16983312581574338606-128.png"class="contact_icon"/></a>
      
    <a href="tel:555-555-5555" class="btn contact-details" target="_blank"
      ><img src="https://i.postimg.cc/Qx9SWcm2/9949026731579517867-128.png" class="contact_icon"/></a>
  </div>
</section>

<footer>
  <div>This is my first web page development portfolio! Keep learning! </div>
</footer>
</body>
</html>
* {
  box-sizing: inherit;
  margin: 0;
  padding: 0;
}
body {
  font-size: 1.8rem;
  font-weight: 400;
  line-height: 1.4;
  font-family: system-ui;
}
html {
  box-sizing: border-box;
}
@media screen and (min-width: 480px){
h1,
h2 {
  font-weight: 700;
  text-align: center;
  color: white;
}
h1 {
  font-size: 6rem;
}
h2 {
  font-size: 4.2rem;
}
h3 {
  font-size: 2rem;
}
.nav {
  display: flex;
  justify-content: flex-end;
  position: fixed;
  width: 100%;
  top: 0;
  left: 0;
  background-color:#b02a45;
  box-shadow: 0 2px 0 rgba(0, 0, 0, 0.4);
  z-index: 10;
  }
.nav-list {
  display: flex;
  margin-right: 2rem;
  list-style: none;
  float: right;
}
.nav-list a {
  display: block;
  color: white;
  padding: 10px;
  text-decoration: none;
  font-size: 25px;
}
.nav-list a:hover {
  background: #45567d;
}
/*Welcome section*/
#welcome-section {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100vh;
  background-color: #000;
  background-image: linear-gradient(62deg, #3a3d40 0%, #181719 100%);
}

#welcome-section > p{
  color: red;
  font-style: italic;
  font-size: 40px;
  text-align:center;
}
/*Project section*/
.projects-section{
  background-color:#45567d;
  width:100%;
  text-align:center;
  display: flex;
  flex-wrap:wrap;
  flex-direction: row;
  }
.projects-section-header {
  border-bottom: 0.2rem solid white;
  margin: 4rem auto 6rem auto;
}
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  grid-gap: 4rem;
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  margin-bottom: 6rem;
}
.project-image {
  height: calc(100% - 6.8rem);
  width: 100%;
  object-fit: cover;
}
.project-tile {
  text-decoration: none;
}
.text-block {
  position: relative;
  background-color: #000;
  background-image: linear-gradient(62deg, #3a3d40 0%, #181719 100%);
  color: white;
  padding: 1rem 0.5rem;
}

 /*Contact section*/
 .contact-section {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  width: 100%;
  height: 80vh;
  padding: 0 2rem;
  background-color: #000;
  background-image: linear-gradient(62deg, #3a3d40 0%, #181719 100%);
}
.contact-section-header >p {
  color:white;
  font-style: italic;
}
.contact-links {
  display: flex;
  justify-content: center;
  width: 100%;
  max-width: 980px;
  margin-top: 4rem;
  flex-wrap: wrap;
}
.contact_icon {
  padding: 20px;
  height:150px;
}

.contact-details:hover {
  transform: translateY(8px);
}
/*Footer section*/
footer {
  height:100px;
  font-weight: 300;
  display: flex;
  justify-content: space-evenly;
  padding: 2rem;
  border-top: 4px solid #b02a45;
  }
  
}

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.5005.63 Safari/537.36

Challenge: Build a Personal Portfolio Webpage

Link to the challenge:

We can’t see your code. so its hard to know what’s wrong.

Sorry! This is the first time I’ve posted a question. I edited my post. Thanks in advance!