Product Landing Page Failing navbar Test

Hi. My product landing page is falling one test:

  1. The navbar should always be at the top of the viewport.

However, I have tested the webpage in all devices, and the navbar is always at the top. Could someone, please, help me identify what’s wrong here? Thanks!
Here’s the GitHub link:

The HTML code:

<!DOCTYPE html>
<html  lang="en" dir="ltr">
	<head>
		<meta charset="UTF-8" />
		<meta name="viewport" content="width=device-width, initial-scale=1"/>
		<meta name="description" content="A mock product page for the Nike Air Max 90"/>
		<title>Product Page</title>
		<!-- styling -->
		<link href="style.css" rel="stylesheet"/>
		<link href="https://fonts.googleapis.com/css2?family=Montserrat:wght@300;400;700;900&display=swap" rel="stylesheet">
		<link href="https://fonts.googleapis.com/css2?family=Muli:wght@300;400;500&display=swap" rel="stylesheet">
	</head>
	<body>
		<!-- free code camp test suit -->
		<script src="https://cdn.freecodecamp.org/testable-projects-fcc/v1/bundle.js"></script>
		<!-- The Beginning of the page code -->
		<header id="header">
			<img src="https://www.logosurfer.com/wp-content/uploads/2018/03/nike-logo_0.png" id="header-img" alt="Nike Logo"/>
			<nav id="nav-bar">
				<ul class="nav-links">
					<li><a class="nav-link" href="#design">DESIGN</a></li>
					<li><a class="nav-link" href="#origin">ORIGIN</a></li>
					<li><a class="nav-link" href="#shop">SHOP</a></li>
				</ul>
			</nav>
		</header>
		<main class="content" id="main-doc">
			<div class="container">
				<!-- PRODUCT NAME AND IMAGE -->
				<section class="main-section theProduct">
					<h1 class="product-title">AIR MAX 90</h1>
					<img src="images/airMax-main(small).jpg" alt="A picture of the Air Max 90' class='product-img"/>
				</section>
				<!-- PRODUCT INFO AND PRICE -->
				<section class="main-section  shop">
					<h3><a id="shop">Women's Shoe</a></h3>
					<p>$120</p>
					<a>Free Shipping & Returns*</a>
					<div class="color">
						<label class="disabled" data-bind="text: colourLabel, visible: !hideLabels">COLOR:</label>
						<span class="product-colour" data-bind="visible: colourLabelVisible(), text: selectedColourLabel(), css: { disabled: isDisabled }">Multi</span>
					</div>
					<div>
						<label for="sizeSelect" style="display: table-cell; vertical-align: bottom" data-bind="text: sizeLabel, visible: !hideLabels, disable: isDisabled">SIZE:</label>
						<select id="sizeSelect">
                        	<option value="">Please select</option>
                            <option value="">US 6</option><option value="">US 6.5</option><option value="">US 7</option><option value="">US 7.5</option><option value="">US 8</option><option value="">US 8.5</option><option value="">US 9</option><option value="">US 9.5</option><option value="">US 10</option><option value="">US 10.5</option><option value="">US 11</option><option value="">US 11.5</option><option value="">US 12</option><option value="">US 12.5</option><option value="">US 13</option><option value="">US 14</option>
						</select>
					</div>
					<p><button>Add to Cart</button></p>
				</section>
			</div>

			<!-- DESIGN -->
			<section class="main-section design">
				<h2><a id="design">HERITAGE STYLE. MODERN COMFORT.</a></h2>
				<p>Clean lines, versatile and timeless—the people's shoe returns with the Nike Air Max 90. Featuring the same iconic Waffle sole, stitched overlays and classic TPU accents you've come to love, it lets you walk among the pantheon of Air.</p>
				<h3>Low-Profile Style</h3>
				<p>The low-top design combines with padded collar for a sleek look that feels soft and comfortable.</p>
				<h3>Performance Comfort</h3>
				<p>Originally designed for performance running, the Max Air unit adds unbelievable cushioning.</p>
				<h3>Nike DNA</h3>
				<p>The rubber Waffle sole adds traction, durability and heritage style.</p>
				<h3>Retro Appeal</h3>
				<p>Stitched overlays and TPU accents add durability, comfort and the iconic '90s look you love.</p>
				<h3>More Benefits</h3>
				<p>The foam midsole adds cushioning that lasts.</p>
			</section>
			<!-- ORIGIN -->
			<section class="main-section origin">
				<h2><a id="origin">Nike Air Max Origins</a></h2>
				<p>Revolutionary Air technology first made its way into Nike footwear in 1978. In 1987, the Air Max 1 debuted with visible Air technology in its heel, allowing fans more than just the feel of Air cushioning—suddenly they could see it. Since then, next-generation Air Max shoes have become a hit with athletes and collectors by offering striking color combinations and reliable, lightweight cushioning.</p>
				<video id="video" controls>
					<source src="/media/%20SD360p-walk-the-90s-with-Giorgia-Faggi.mp4%20.mp4" type="video/mp4"/>Sorry, your browser doesn't support embedded videos.
				</video>
			</section>
		</main>
		<footer>
			<form id="form" action=" https://www.freecodecamp.com/email-submit" method="post" enctype="text/plain">
				<div>
					<p>Enter your email to be notified of sales, new realeases and more!</p>
					<label class="email" for="email"><b>Email:</b></label><br>
						<input type="email" placeholder="Enter Email" name="email" id="email" required>
						<input id="submit" type="submit" value="Sign Up" class="btn" />
				</div>
			</form>
		</footer>
	</body>
</html>

The CSS code:

/*! normalize.css v8.0.1 | MIT License | github.com/necolas/normalize.css */

/* Document
   ========================================================================== */

/**
 * 1. Correct the line height in all browsers.
 * 2. Prevent adjustments of font size after orientation changes in iOS.
 */

 html {
  line-height: 1.15; /* 1 */
  -webkit-text-size-adjust: 100%; /* 2 */
}

/* Sections
   ========================================================================== */

/**
 * Remove the margin in all browsers.
 */

body {
  margin: 0;
}

/**
 * Render the `main` element consistently in IE.
 */

main {
  display: block;
}

/**
 * Correct the font size and margin on `h1` elements within `section` and
 * `article` contexts in Chrome, Firefox, and Safari.
 */

h1 {
  font-size: 2em;
  margin: 0.67em 0;
}

/* Grouping content
   ========================================================================== */

/**
 * 1. Add the correct box sizing in Firefox.
 * 2. Show the overflow in Edge and IE.
 */

hr {
  box-sizing: content-box; /* 1 */
  height: 0; /* 1 */
  overflow: visible; /* 2 */
}

/**
 * 1. Correct the inheritance and scaling of font size in all browsers.
 * 2. Correct the odd `em` font sizing in all browsers.
 */

pre {
  font-family: monospace, monospace; /* 1 */
  font-size: 1em; /* 2 */
}

/* Text-level semantics
   ========================================================================== */

/**
 * Remove the gray background on active links in IE 10.
 */

a {
  background-color: transparent;
}

/**
 * 1. Remove the bottom border in Chrome 57-
 * 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
 */

abbr[title] {
  border-bottom: none; /* 1 */
  text-decoration: underline; /* 2 */
  text-decoration: underline dotted; /* 2 */
}

/**
 * Add the correct font weight in Chrome, Edge, and Safari.
 */

b,
strong {
  font-weight: bolder;
}

/**
 * 1. Correct the inheritance and scaling of font size in all browsers.
 * 2. Correct the odd `em` font sizing in all browsers.
 */

code,
kbd,
samp {
  font-family: monospace, monospace; /* 1 */
  font-size: 1em; /* 2 */
}

/**
 * Add the correct font size in all browsers.
 */

small {
  font-size: 80%;
}

/**
 * Prevent `sub` and `sup` elements from affecting the line height in
 * all browsers.
 */

sub,
sup {
  font-size: 75%;
  line-height: 0;
  position: relative;
  vertical-align: baseline;
}

sub {
  bottom: -0.25em;
}

sup {
  top: -0.5em;
}

/* Embedded content
   ========================================================================== */

/**
 * Remove the border on images inside links in IE 10.
 */

img {
  border-style: none;
}

/* Forms
   ========================================================================== */

/**
 * 1. Change the font styles in all browsers.
 * 2. Remove the margin in Firefox and Safari.
 */

button,
input,
optgroup,
select,
textarea {
  font-family: inherit; /* 1 */
  font-size: 100%; /* 1 */
  line-height: 1.15; /* 1 */
  margin: 0; /* 2 */
}

/**
 * Show the overflow in IE.
 * 1. Show the overflow in Edge.
 */

button,
input { /* 1 */
  overflow: visible;
}

/**
 * Remove the inheritance of text transform in Edge, Firefox, and IE.
 * 1. Remove the inheritance of text transform in Firefox.
 */

button,
select { /* 1 */
  text-transform: none;
}

/**
 * Correct the inability to style clickable types in iOS and Safari.
 */

button,
[type="button"],
[type="reset"],
[type="submit"] {
  -webkit-appearance: button;
}

/**
 * Remove the inner border and padding in Firefox.
 */

button::-moz-focus-inner,
[type="button"]::-moz-focus-inner,
[type="reset"]::-moz-focus-inner,
[type="submit"]::-moz-focus-inner {
  border-style: none;
  padding: 0;
}

/**
 * Restore the focus styles unset by the previous rule.
 */

button:-moz-focusring,
[type="button"]:-moz-focusring,
[type="reset"]:-moz-focusring,
[type="submit"]:-moz-focusring {
  outline: 1px dotted ButtonText;
}

/**
 * Correct the padding in Firefox.
 */

fieldset {
  padding: 0.35em 0.75em 0.625em;
}

/**
 * 1. Correct the text wrapping in Edge and IE.
 * 2. Correct the color inheritance from `fieldset` elements in IE.
 * 3. Remove the padding so developers are not caught out when they zero out
 *    `fieldset` elements in all browsers.
 */

legend {
  box-sizing: border-box; /* 1 */
  color: inherit; /* 2 */
  display: table; /* 1 */
  max-width: 100%; /* 1 */
  padding: 0; /* 3 */
  white-space: normal; /* 1 */
}

/**
 * Add the correct vertical alignment in Chrome, Firefox, and Opera.
 */

progress {
  vertical-align: baseline;
}

/**
 * Remove the default vertical scrollbar in IE 10+.
 */

textarea {
  overflow: auto;
}

/**
 * 1. Add the correct box sizing in IE 10.
 * 2. Remove the padding in IE 10.
 */

[type="checkbox"],
[type="radio"] {
  box-sizing: border-box; /* 1 */
  padding: 0; /* 2 */
}

/**
 * Correct the cursor style of increment and decrement buttons in Chrome.
 */

[type="number"]::-webkit-inner-spin-button,
[type="number"]::-webkit-outer-spin-button {
  height: auto;
}

/**
 * 1. Correct the odd appearance in Chrome and Safari.
 * 2. Correct the outline style in Safari.
 */

[type="search"] {
  -webkit-appearance: textfield; /* 1 */
  outline-offset: -2px; /* 2 */
}

/**
 * Remove the inner padding in Chrome and Safari on macOS.
 */

[type="search"]::-webkit-search-decoration {
  -webkit-appearance: none;
}

/**
 * 1. Correct the inability to style clickable types in iOS and Safari.
 * 2. Change font properties to `inherit` in Safari.
 */

::-webkit-file-upload-button {
  -webkit-appearance: button; /* 1 */
  font: inherit; /* 2 */
}

/* Interactive
   ========================================================================== */

/*
 * Add the correct display in Edge, IE 10+, and Firefox.
 */

details {
  display: block;
}

/*
 * Add the correct display in all browsers.
 */

summary {
  display: list-item;
}

/* Misc
   ========================================================================== */

/**
 * Add the correct display in IE 10+.
 */

template {
  display: none;
}

/**
 * Add the correct display in IE 10.
 */

[hidden] {
  display: none;
}

/** ==========================================================================
 *  This is the beginning of my own code, after CSS reset.
 */

:root {
  --white: #F2F2F2;
	--silver-pink: #D7B4AE;
	--coper-penny: #AE675B;
	--purple: #7F00FF;
	--dark-purple: #3B243E;
	--pink: #E100FF;
	--orange: #CF4011;
	--blue: #08083A;
	--acqua-blue: #11CFCC;
}

html {
	font-size: 62.5%; /* =10px */
}

body {
	background-color: var(--silver-pink);
	font-family: 'Muli', sans-serif;
	color: #200811;
	font-size: 1.6rem;
	font-size: 16px;
	letter-spacing: 0.2rem;
}

/**
 * Header ================================================
 */

#header {
	padding-bottom: 20px;
}

#header-img {
  max-width: 5%;
  margin-top: 5px;
  float: left;
  padding-left: 10px;
  text-align: center;
}

.nav-links, .nav-link {
	list-style-type: none; /* eliminate the bullet points */
	display: block;
	color: white;
	float: right;
	text-align: center;
	padding-right: 10px;
	text-decoration: none; /* eliminate the underline */
}

/* Change link background color when active */
a:active {
	color: var(--pink);
}

/* Change link text color on hoover */
a:hoover {
	color: var(--orange);
}

ul {
	margin: 0;
	padding: 0;
	overflow: hidden;
}

li {
  float: right;
}

/**
 * Main ================================================
 */

/* eliminate the space between the main and the footer */
main {
	overflow: hidden;
}

section {
	padding: 10px;
}

.product-title {
	font-family: 'Montserrat', sans-serif;
	font-weight: 900;
	font-size: 5rem;
	font-size: 50px;
	text-transform: uppercase;
	color: var(--acqua-blue);
	text-align: center;
	text-shadow: 1px 1px 2px black, 3px 3px var(--pink);
	margin-bottom: 0;
	/* to bring the text closer to the image: */
	position: relative;
	top: 9px;
}

h2 {
	font-family: 'Montserrat', sans-serif;
	font-weight: 700;
	font-size: 2.5rem;
	font-size: 25px;
	text-transform: uppercase;
	color: white;
	text-align: center;
}

img {
	max-width: 100%;
}

.product-img {
	display: block;
	margin-left: auto;
	margin-right: auto;
}

.shop, footer {
	padding: 10px;
}

.shop {
	background-color: #08083A;
	color: white;
	height: 100%;
}

.shop a {
	text-decoration: underline;
}

.shop button {
  border: none;
  outline: 0;
  padding: 12px;
  color: white;
  background-color: var(--acqua-blue);
  text-align: center;
  cursor: pointer;
  width: 100%;
  font-size: 18px;
}

button:hover {
  opacity: 0.7;
}

.color {
	padding-top: 40px;
}

div {
	padding: 10px 0;
}

label {
	padding-bottom: 10px;
}

#sizeSelect {
    width: 100%;
    color: #2D2D2D;
    border: solid 1px #999;
    font-size: 16px;
    line-height: 1.0;
    letter-spacing: 0.4px;
    padding-top: 9px;
    padding-bottom: 9px;
    padding-left: 14px;
    outline: none;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
* {
    -ms-content-zooming: none;
}

.design h3,
.design p,
.design h3,
.origin p {
	text-align: center;
}

#video {
	width: 100%;
}

/**
 * Footer ================================================
 */

footer {
	background-color: #CF4011;
}

#form {
	padding-right: 10px;
}

form, #form p {
	color: white;

}

.email {
	margin-bottom: 10px;
}

#email {
	width: 100%;
	margin-top: 10px;
}

.btn {
  margin-top: .75rem;
  display: block;
  font-size: 14px;
  letter-spacing: 1px;
  padding: 0.4rem 5.4rem;
  border-radius: 4px;
  color: white;
  background: var(--acqua-blue);
  border: 1px solid var(--acqua-blue);
  box-shadow: 3px 3px 3px 2px rgba(0, 0, 0, 0.4);
}

.btn:hover {
  background-color: #4b5872;
}

.btn:active {
  background-color: #4b5872;
  transform: translateY(3px);
}

@media screen and (min-width: 850px) {

	body {
		margin: 0 40px;
	}

	.container {
		display: flex;
		justify-content: flex-start;
	}

	.theProduct {
		width: 70%;
	}

	.shop {
		margin-top: 100px; /* to align with the section .theProduct */
		width: 30%;
		height: 360px;
	}

	body  {
    	width: 850px;
    	margin-left: auto;
    	margin-right: auto;
		margin-bottom: 40px;
	}
}

Hi, on your #header write

position: fixed;
width : 100%;
top: 0;

You should be good with that

This worked. Thank you for your help!

It’s my pleasure being able to help. Best