Technical documentation page test, media query problem

Hi there, I’m having a problem with my media query in the technical documentation assignment. I’ve tried many media query (also copied some from the forums and internet), but nothing seems to be working. Can someone tell me what’s wrong with it please?

!DOCTYPE html>

Technical Documentation Page - FreeCodeCamp
<nav id="navbar">
  <header id="main-header">
  <h1>JS Documentation</h1>
    <li><a  class="nav-link" href="#Introduction">Introduction</a></li>
    <li><a  class="nav-link" href="#What_you_should_already_know">What you should already know</a></li>
    <li><a href="#JavaScript_and_Java"  class="nav-link">JavaScript and Java</a></li>
    <li><a href="#Hello_World"  class="nav-link">Hello world</a></li>
    <li><a href="#Variables" class="nav-link">Variables</a></li>
    <li><a  class="nav-link" href="#Declaring_variables">Declaring variables</a></li>
    <li><a  class="nav-link" href="#Variable_scope">Variable scope</a></li>
    <li><a  class="nav-link" href="#Global_variables">Global variables</a></li>
    <li><a  class="nav-link" href="#Constants">Constants</a></li>
    <li><a  class="nav-link" href="#Data_types">Data types</a></li>
    <li><a  class="nav-link" href="#if...else_statement">if...else statement</a></li>
    <li><a  class="nav-link" href="#While_statement">while statement</a></li>
    <li><a  class="nav-link" href="#Function_declarations">Function declarations</a></li>
    <li><a  class="nav-link" href="#Reference">Reference</a></li>

JavaScript is a cross-platform, object-oriented scripting language. It is a small and lightweight language. Inside a host environment (for example, a web browser), JavaScript can be connected to the objects of its environment to provide programmatic control over them.

JavaScript contains a standard library of objects, such as Array, Date, and Math, and a core set of language elements such as operators, control structures, and statements. Core JavaScript can be extended for a variety of purposes by supplementing it with additional objects; for example:

  • Client-side JavaScript extends the core language by supplying objects to control a browser and its Document Object Model (DOM). For example, client-side extensions allow an application to place elements on an HTML form and respond to user events such as mouse clicks, form input, and page navigation.
  • Server-side JavaScript extends the core language by supplying objects relevant to running JavaScript on a server. For example, server-side extensions allow an application to communicate with a database, provide continuity of information from one invocation to another of the application or perform file manipulations on a server....
<section class="main-section" id="What_you_should_already_know">
  <header>What you should already know</header>
  <article class="main-article">
    <p>This guide assumes you have the following basic background:</p>
      <li>A general understanding of the Internet and the World Wide Web (WWW).</li>
      <li>Good working knowledge of HyperText Markup Language (HTML).</li>
      <li>Some programming experience. If you are new to programming, try one of the tutorials linked on the main
        page about JavaScript.</li>

<section class="main-section" id="JavaScript_and_Java">
  <header>JavaScript and Java</header>
  <article class="main-article">
    <p>JavaScript and Java are similar in some ways but fundamentally different in some others. The JavaScript
      language resembles Java but does not have Java's static typing and strong type checking. JavaScript follows
      most Java expression syntax, naming conventions and basic control-flow constructs which was the reason why it
      was renamed from LiveScript to JavaScript.</p>
    <p>In contrast to Java's compile-time system of classes built by declarations, JavaScript supports a runtime
      system based on a small number of data types representing numeric, Boolean, and string values. JavaScript has
      a prototype-based object model instead of the more common class-based object model. The prototype-based model
      provides dynamic inheritance; that is, what is inherited can vary for individual objects. JavaScript also
      supports functions without any special declarative requirements. Functions can be properties of objects,
      executing as loosely typed methods.</p>
    <p>JavaScript is a very free-form language compared to Java. You do not have to declare all variables, classes,
      and methods. You do not have to be concerned with whether methods are public, private, or protected, and you
      do not have to implement interfaces. Variables, parameters, and function return types are not explicitly

<section class="main-section" id="Hello_World">
  <header>Hello world</header>
  <article class="main-article">
    <p>To get started with writing JavaScript, open the Scratchpad and write your first "Hello world" JavaScript
    <code>function greetMe(yourName) { alert("Hello " + yourName); }
    <p>Select the code in the pad and hit Ctrl+R to watch it unfold in your browser!</p>

<section class="main-section" id="Variables">
  <article class="main-article">
    <p>You use variables as symbolic names for values in your application. The names of variables, called
      identifiers, conform to certain rules.</p>
    <p>A JavaScript identifier must start with a letter, underscore (_), or dollar sign ($); subsequent characters
      can also be digits (0-9). Because JavaScript is case sensitive, letters include the characters "A" through "Z"
      (uppercase) and the characters "a" through "z" (lowercase).</p>
    <p>You can use ISO 8859-1 or Unicode letters such as å and ü in identifiers. You can also use the Unicode escape
      sequences as characters in identifiers. Some examples of legal names are Number_hits, temp99, and _name.</p>

<section class="main-section" id="Declaring_variables">
  <header>Declaring variables</header>
  <article class="main-article">
    <p>You can declare a variable in three ways:</p>
    <p>With the keyword var. For example,</p>
    <code>var x = 42.</code>
    <p>This syntax can be used to declare both local and global variables.</p>
    <p>By simply assigning it a value. For example,</p>
    <code>x = 42.</code>
    <p>This always declares a global variable. It generates a strict JavaScript warning. You shouldn't use this
    <p>With the keyword let. For example,</p>
    <code>let y = 13.</code>
    <p>This syntax can be used to declare a block scope local variable. See Variable scope below.</p>

<section class="main-section" id="Variable_scope">
  <header>Variable scope</header>
  <article class="main-article">
    <p>When you declare a variable outside of any function, it is called a global variable, because it is available
      to any other code in the current document. When you declare a variable within a function, it is called a local
      variable, because it is available only within that function.</p>
    <p>JavaScript before ECMAScript 2015 does not have block statement scope; rather, a variable declared within a
      block is local to the function (or global scope) that the block resides within. For example the following code
      will log 5, because the scope of x is the function (or global context) within which x is declared, not the
      block, which in this case is an if statement.</p>
    <code>if (true) { var x = 5; } console.log(x); // 5</code>
    <p>This behavior changes, when using the let declaration introduced in ECMAScript 2015</p>
    <code>if (true) { let y = 5; } console.log(y); // ReferenceError: y is not

<section class="main-section" id="Global_variables">
  <header>Global variables</header>
  <article class="main-article">
    <p>Global variables are in fact properties of the global object. In web pages the global object is window, so
      you can set and access global variables using the window.variable syntax.</p>
    <p>Consequently, you can access global variables declared in one window or frame from another window or frame by
      specifying the window or frame name. For example, if a variable called phoneNumber is declared in a document,
      you can refer to this variable from an iframe as parent.phoneNumber.</p>

<section class="main-section" id="Constants">
  <article class="main-article">
    <p>You can create a read-only, named constant with the const keyword. The syntax of a constant identifier is the
      same as for a variable identifier: it must start with a letter, underscore or dollar sign and can contain
      alphabetic, numeric, or underscore characters.</p>
    <code>const PI = 3.14;</code>
    <p>A constant cannot change value through assignment or be re-declared while the script is running. It has to be
      initialized to a value.</p>
    <p>The scope rules for constants are the same as those for let block scope variables. If the const keyword is
      omitted, the identifier is assumed to represent a variable.</p>
    <p>You cannot declare a constant with the same name as a function or variable in the same scope. For example:
    <code>// THIS WILL CAUSE AN ERROR function f() {}; const f = 5; // THIS WILL
      CAUSE AN ERROR ALSO function f() { const g = 5; var g; //statements
    <p>However, object attributes are not protected, so the following statement is executed without problems.</p>
    <code>const MY_OBJECT = {"key": "value"}; MY_OBJECT.key = "otherValue";</code>

<section class="main-section" id="Data_types">
  <header>Data types</header>
  <article class="main-article">
    <p>The latest ECMAScript standard defines seven data types:</p>
        <p>Six data types that are primitives:</p>
          <li>Boolean. true and false.</li>
          <li>null. A special keyword denoting a null value. Because JavaScript is case-sensitive, null is not the
            same as Null, NULL, or any other variant.</li>
          <li>undefined. A top-level property whose value is undefined.</li>
          <li>Number. 42 or 3.14159.</li>
          <li>String. "Howdy"</li>
          <li>Symbol (new in ECMAScript 2015). A data type whose instances are unique and immutable.</li>
      <li>and Object</li>

<section class="main-section" id="if...else_statement">
  <header>if...else statement</header>
  <article class="main-article">
    <p>Use the if statement to execute a statement if a logical condition is true. Use the optional else clause to
      execute a statement if the condition is false. An if statement looks as follows:</p>
    <code>if (condition) { statement_1; } else { statement_2; }</code>
    <p>condition can be any expression that evaluates to true or false. See Boolean for an explanation of what
      evaluates to true and false. If condition evaluates to true, statement_1 is executed; otherwise, statement_2
      is executed. statement_1 and statement_2 can be any statement, including further nested if statements.</p>
    <p>You may also compound the statements using else if to have multiple conditions tested in sequence, as
    <code>if (condition_1) { statement_1; } else if (condition_2) { statement_2;
      } else if (condition_n) { statement_n; } else { statement_last; }</code>
    <p>In the case of multiple conditions only the first logical condition which evaluates to true will be executed.
      To execute multiple statements, group them within a block statement ({ ... }) . In general, it's good practice
      to always use block statements, especially when nesting if statements:</p>
    <code>if (condition) { statement_1_runs_if_condition_is_true;
      statement_2_runs_if_condition_is_true; } else {
      statement_4_runs_if_condition_is_false; }</code>
    <p>It is advisable to not use simple assignments in a conditional expression, because the assignment can be
      confused with equality when glancing over the code. For example, do not use the following code:</p>
    <code>if (x = y) { /* statements here */ }</code>
    <p>If you need to use an assignment in a conditional expression, a common practice is to put additional
      parentheses around the assignment. For example:</p>
    <code>if ((x = y)) { /* statements here */ }</code>

<section class="main-section" id="While_statement">
  <header>while statement</header>
  <article class="main-article">
    <p>A while statement executes its statements as long as a specified condition evaluates to true. A while
      statement looks as follows:</p>
    <code>while (condition) statement</code>
    <p>If the condition becomes false, statement within the loop stops executing and control passes to the statement
      following the loop.</p>
    <p>The condition test occurs before statement in the loop is executed. If the condition returns true, statement
      is executed and the condition is tested again. If the condition returns false, execution stops and control is
      passed to the statement following while.</p>
    <p>To execute multiple statements, use a block statement ({ ... }) to group those statements.</p>
    <p>The following while loop iterates as long as n is less than three:</p>
    <code>var n = 0; var x = 0; while (n &lt; 3) { n++; x += n; }</code>
    <p>With each iteration, the loop increments n and adds that value to x. Therefore, x and n take on the following
      <li>After the first pass: n = 1 and x = 1</li>
      <li>After the second pass: n = 2 and x = 3</li>
      <li>After the third pass: n = 3 and x = 6</li>
    <p>After completing the third pass, the condition n &lt; 3 is no longer true, so the loop terminates.</p>

<section class="main-section" id="Function_declarations">
  <header>Function declarations</header>
  <article class="main-article">
    <p>A function definition (also called a function declaration, or function statement) consists of the function
      keyword, followed by:</p>
      <li>The name of the function.</li>
      <li>A list of arguments to the function, enclosed in parentheses and separated by commas.</li>
      <li>The JavaScript statements that define the function, enclosed in curly brackets, { }.</li>
    <p>For example, the following code defines a simple function named square:</p>
    <code>function square(number) { return number * number; }</code>
    <p>The function square takes one argument, called number. The function consists of one statement that says to
      return the argument of the function (that is, number) multiplied by itself. The return statement specifies the
      value returned by the function.</p>
    <code>return number * number;</code>
    <p>Primitive parameters (such as a number) are passed to functions by value; the value is passed to the
      function, but if the function changes the value of the parameter, this change is not reflected globally or in
      the calling function.</p>

<section class="main-section" id="Reference">
  <article class="main-article">
      <li>All the documentation in this page is taken from <a
  • {
    margin: 0;

body {
font-family: ‘Segoe UI’, Tahoma, Geneva, Verdana, sans-serif;
line-height: 1.5;
background-color: #f1f1f1;

#main-header {
position: fixed;
top: 0;
left: 0;
height: 100%;
min-width: 280px;
max-width: 300px;

#navbar {
height: 100%;
border-right: solid 2.5px #333;

#navbar>h1 {
font-size: 1.6rem;
text-align: center;
padding: 1rem 0;

#navbar ul {
padding: 0;
overflow-y: auto;
overflow-x: hidden;
height: 90%;
list-style: none;

#navbar ul li {
border: solid 1.3px #333;

#main-header #navbar ul li a {
display: block;
text-align: left;
padding: .8rem 1rem .8rem 2rem;
cursor: pointer;
color: #222;
text-decoration: none;

/* main section */
#main-doc {
position: absolute;
margin-left: 320px;
padding: 2rem 1rem;

#main-doc .main-section header {
font-size: 2rem;
padding: 1rem 0;

#main-doc .main-section .main-article {
padding-left: 1.5rem;
margin-bottom: .5rem;
color: #222;

#main-doc .main-section .main-article p {
margin-bottom: 1rem;

#main-doc .main-section .main-article ul {
margin: 1.3rem 0 0 1.2rem;

#main-doc .main-section .main-article ul li {
margin-bottom: 1rem;

#main-doc .main-section .main-article code {
display: block;
padding: 1.5rem;
text-align: left;
background-color: #ddd;
border-radius: 7px;
margin-bottom: 1rem;

#main-doc .main-section:last-child .main-article ul {
margin: .5rem 0 1.5rem 3rem;
padding: 0;

#creator {
text-align: left;
padding: 2rem 0 0;

#navbar {
width: 100%;
margin: 0;

#main-doc {
position: relative;
margin-left: 0px;
padding: 2rem 1rem;
margin-top: 410px;

@media only screen and (max-width: 478px) {
color: lightgreen;

Hello @cartesanicolo !

It appears the basic boiler template is missing. Or, if that is there, it may be that there is a bit of problem with the link to the CSS file.

I will tell you that once I added the boiler plate and made a slight adjustment that the media query was recognized.

I am thinking you are just starting off with the CSS requirement and will continue working on the html

Here is a good validator to check html and CSS for errors.

Ready to check - Nu Html Checker

Wishing you good progress.

Thank you so much! I’ll try to check my boilerplate right away

1 Like

You are very welcome @cartesanicolo !

If there are still issues, please post on this post and somebody in the community will help guide you to a resolution.

Here is a link to an great article with examples to media query.

Wishing you more good progress!

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