Technical Documentation Page - Build a Technical Documentation Page

hello everyone. I am unable to resolve the following issue
// Each .main-section should have an id that matches the text of its first child, having any spaces in the child’s text replaced with underscores (_ ) for the id’s.//

<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Documentation Page</title>
    <link rel="stylesheet" href="styles.css">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
  <body>
      <nav id="navbar">
            <header id="main-header">

        <h1>JS Documentation</h1>
        <ul>
          <a class="nav-link" href="#introduction"><li>Introduction</li></a>
          <a class="nav-link" href="#what_you"><li>What You Should Already Know</li></a>
          <a class="nav-link" href="#javascript_and_java"><li>JavaScript And Java</li></a>
          <a class="nav-link" href="#hello_world"><li>Hello World</li></a>
          <a class="nav-link" href="#variables"><li>Variables</li></a>
          <a class="nav-link" href="#declaring_variables"><li>Declaring Variables</li></a>
          <a class="nav-link" href="#global_variables"><li>Global Variables</li></a>
          <a class="nav-link" href="#constants"><li>Constants</li></a>
          <a class="nav-link" href="#data_types"><li>Data Types</li></a>
          <a class="nav-link" href="#if_else"><li>if...else Statement</li></a>
          <a class="nav-link" href="#while_statement"><li>While Statement</li></a>
          <a class="nav-link" href="#function_declarations"><li>Function Declarations</li></a>
          <a class="nav-link" href="#reference"><li>Reference</li></a>
          <a class="nav-link" href="#variable_scope"><li>Variable Scope</li></a>
</ul>
</nav>
</header>
<main id="main-doc">
  <section class="main-section" id="introduction">
    <header>Introduction</header>
    <article class="main-article">
      <p>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.</p>
        <p>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: </p>
        <ul>
           <li>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.</li>
          <li>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....</li>
        </ul>
      </article>
    </section> 
    <section class="main-section" id="what_you">
      <header>What You Should Already Know </header>
      <article class="main-article">
        <p>this guide assumes you have the following basic background: </p>
        <ul>
          <li>A general understanding of the Internet and World Wide Web (WWW).</li>
          <li>Good working knowledge of HyperText Markup Language (HTML). </li>
          <li>some programming experience. If you are new tp programming, try one of the tutorials linked on tje main page about JavaScript. </li>
          </ul>
          </article>
          </section>
          <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 dyanmic inheritance; that is, what is inherited can vary from 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
          typed.</p>
          </ul>
          </article>
          </section>

          <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: </p>
              <code>function greetMe(yourName) {alert("Hello" + yourName);}
                greetMe("World");</code>
                <p>Select the code in the pad and hit Ctrl+R to watch it unfold in your browser! </p>
                </article>
                </section>

                <section class="main-section" id="variables">
                  <header>Variables</header>
                  <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>
          </article>
          </section>

          <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 synatx 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 variant. </p>
              <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>
              </article>
              </section>
<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 defined </code>
          </article>
          </section>
           
           <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>
          </article>
          </section>
           <section class="main-section " id="constants">
             <header>Constants</header>
             <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 character. </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:</p>
               <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 } </code>
               <p>However, object attributes are not protected, so the following statement is executed without problem. </p>
               <code>const MY_OBJECT = {"key" : "value"}; MY_OBJECT.key = "otherValue"; </code>
               </article>
               </section>
                <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>
                    <ul>
                      <li>
                        <p>Six data types that are primitives: </p>
                        <ul>
                          <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>
                          </ul>
                          <li>and Object</li>
                          </li>
                          </ul>
                          </article>
                          </section>

                          <section class="main-section" id="if_else">
                            <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
          follows:</p>
        <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_3_runs_if_condition_is_false;
          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>
        </article>
        </section>
         <section class="main-section" id="while_statement">
           <header>While Statement</header>
           <article class="main-article">
             <P>While statement executes it statements as long as specified condition evalutes to true. A while statement looks as follows: </p>
             <code>while(condition) statement </code>
             <p>If the condition becomes false, statemnet within the loop stops executing and control passes to the statement following the loop. </p>
             <p>The condition text 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>Example:</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
          values:</p>
        <ul>
          <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>
        </ul>
        <p>After completing the third pass, the condition n &lt; 3 is no longer true, so the loop terminates.</p>
      </article>
    </section>

     <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>
        <ul>
          <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>
        </ul>
        <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>
      </article>
    </section>
<section class="main-section " id="reference">
  <header>Reference</header>
  <article class="main-article">
    <ul>
      <li>All the documentation in this page is taken from <a href="https://developer.mozilla.org/en-US/Web/JavaScript/Guide">MDN</a></li>
      </ul>
      </article>
      </section>
      </main>
    </body>
  </html>

Your code so far

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The challenge seed code and/or your solution exceeded the maximum length we can port over from the challenge.

You will need to take an additional step here so the code you wrote presents in an easy to read format.

Please copy/paste all the editor code showing in the challenge from where you just linked.

Replace these two sentences with your copied code.
Please leave the ``` line above and the ``` line below,
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Challenge: Technical Documentation Page - Build a Technical Documentation Page

Link to the challenge:
https://www.freecodecamp.org/learn/2022/responsive-web-design/build-a-technical-documentation-page-project/build-a-technical-documentation-page`Preformatted text`

Well, lets take a look at this section.

header is it’s first child.

id of the section doesn’t match the text content in the header. So you need to fix this one and all other sections.

I tried but it didn’t work well

Well, need to see your updated code then.
For this issue I think only html code needed

here is the link of code.
https://www.freecodecamp.org/learn/2022/responsive-web-design/build-a-technical-documentation-page-project/build-a-technical-documentation-page

Unfortunately, it is not

This link redirects me to my own solution for this

You need to paste your code here so we can see it actually

type or paste code here
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Documentation Page</title>
    <link rel="stylesheet" href="styles.css">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    </head>
  <body>
      <nav id="navbar">
            <header id="main-header">

        <h1>JS Documentation</h1>
        <ul>
          <a class="nav-link" href="#introduction"><li>Introduction</li></a>
          <a class="nav-link" href="#what_you"><li>What You Should Already Know</li></a>
          <a class="nav-link" href="#javascript_and_java"><li>JavaScript And Java</li></a>
          <a class="nav-link" href="#hello_world"><li>Hello World</li></a>
          <a class="nav-link" href="#variables"><li>Variables</li></a>
          <a class="nav-link" href="#declaring_variables"><li>Declaring Variables</li></a>
          <a class="nav-link" href="#global_variables"><li>Global Variables</li></a>
          <a class="nav-link" href="#constants"><li>Constants</li></a>
          <a class="nav-link" href="#data_types"><li>Data Types</li></a>
          <a class="nav-link" href="#if_else"><li>if...else Statement</li></a>
          <a class="nav-link" href="#while_statement"><li>While Statement</li></a>
          <a class="nav-link" href="#function_declarations"><li>Function Declarations</li></a>
          <a class="nav-link" href="#reference"><li>Reference</li></a>
          <a class="nav-link" href="#variable_scope"><li>Variable Scope</li></a>
</ul>
</nav>
</header>
<main id="main-doc">
  <section class="main-section" id="introduction">
    <header>Introduction</header>
    <article class="main-article">
      <p>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.</p>
        <p>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: </p>
        <ul>
           <li>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.</li>
          <li>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....</li>
        </ul>
      </article>
    </section> 
    <section class="main-section" id="what_you">
      <header>What You Should Already Know </header>
      <article class="main-article">
        <p>this guide assumes you have the following basic background: </p>
        <ul>
          <li>A general understanding of the Internet and World Wide Web (WWW).</li>
          <li>Good working knowledge of HyperText Markup Language (HTML). </li>
          <li>some programming experience. If you are new tp programming, try one of the tutorials linked on tje main page about JavaScript. </li>
          </ul>
          </article>
          </section>
          <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 dyanmic inheritance; that is, what is inherited can vary from 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
          typed.</p>
          </ul>
          </article>
          </section>

          <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: </p>
              <code>function greetMe(yourName) {alert("Hello" + yourName);}
                greetMe("World");</code>
                <p>Select the code in the pad and hit Ctrl+R to watch it unfold in your browser! </p>
                </article>
                </section>

                <section class="main-section" id="variables">
                  <header>Variables</header>
                  <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>
          </article>
          </section>

          <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 synatx 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 variant. </p>
              <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>
              </article>
              </section>
<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 defined </code>
          </article>
          </section>
           
           <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>
          </article>
          </section>
           <section class="main-section " id="constants">
             <header>Constants</header>
             <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 character. </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:</p>
               <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 } </code>
               <p>However, object attributes are not protected, so the following statement is executed without problem. </p>
               <code>const MY_OBJECT = {"key" : "value"}; MY_OBJECT.key = "otherValue"; </code>
               </article>
               </section>
                <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>
                    <ul>
                      <li>
                        <p>Six data types that are primitives: </p>
                        <ul>
                          <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>
                          </ul>
                          <li>and Object</li>
                          </li>
                          </ul>
                          </article>
                          </section>

                          <section class="main-section" id="if_else">
                            <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
          follows:</p>
        <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_3_runs_if_condition_is_false;
          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>
        </article>
        </section>
         <section class="main-section" id="while_statement">
           <header>While Statement</header>
           <article class="main-article">
             <P>While statement executes it statements as long as specified condition evalutes to true. A while statement looks as follows: </p>
             <code>while(condition) statement </code>
             <p>If the condition becomes false, statemnet within the loop stops executing and control passes to the statement following the loop. </p>
             <p>The condition text 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>Example:</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
          values:</p>
        <ul>
          <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>
        </ul>
        <p>After completing the third pass, the condition n &lt; 3 is no longer true, so the loop terminates.</p>
      </article>
    </section>

     <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>
        <ul>
          <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>
        </ul>
        <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>
      </article>
    </section>
<section class="main-section " id="reference">
  <header>Reference</header>
  <article class="main-article">
    <ul>
      <li>All the documentation in this page is taken from <a href="https://developer.mozilla.org/en-US/Web/JavaScript/Guide">MDN</a></li>
      </ul>
      </article>
      </section>
      </main>
    </body>
  </html>

I am not sure if you fixed the issues I mentioned.

see this:

and this:

Introduction and introduction are not exactly the same.
And that’s the issue.

Same thing could be said about the above also.

And about lower sections.
Case-sensitivity matters here also. Maybe I needed specifically mention it earlier.

thankyou so much . I finally understand the mistake.