Hello everybody!
I checked my code several times, but I don’t find any errors.
• The first child of each .main section must be a header element.
In debug I noticed the problem with TAG <a>, example on line 271.
If I remove an <a> TAG and change it to XML.com plain text, the problem disappears.
Please help me.
Thank you in advance.
<!DOCTYPE hmtl>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Technical Documentation XML</title>
<link rel="stylesheet" href="styles.css">
</head>
<body>
<div id="page-container">
<nav id="navbar">
<header>Technical Documentation XML</header>
<ul>
<li><a class="nav-link" href="#XML_introduction">XML introduction</a></li>
<li><a class="nav-link" href="#Structure_of_an_XML_document">Structure of an XML document</a></li>
<li><a class="nav-link" href="#Correct_XML_valid_and_well_formed">Correct XML valid and well formed</a></li>
<li><a class="nav-link" href="#Entities">Entities</a></li>
<li><a class="nav-link" href="#Displaying_XML">Displaying XML</a></li>
<li><a class="nav-link" href="#Recommendations">Recommendations</a></li>
<li><a class="nav-link" href="#See_also">See also</a></li>
</ul>
</nav>
<div id="main" class="main">
<main id="main-doc">
<div id="sections" class="sections">
<div id="section_XML_introduction" class="section_XML_introduction">
<section id="XML_introduction" class="main-section">
<header>XML introduction</header>
<article>
<p>
XML (Extensible Markup Language) is a markup language similar to <a class="negrito"
href="https://developer.mozilla.org/en-US/docs/Glossary/HTML" target="_blank">HTML</a>, but without
predefined tags to use. Instead, you define your own tags designed specifically for your needs. This is
a powerful way to store data in a format that can be stored, searched, and shared. Most importantly,
since the fundamental format of XML is standardized, if you share or transmit XML across systems or
platforms, either locally or over the internet, the recipient can still parse the data due to the
standardized XML syntax.
</p>
<p>
There are many languages based on XML, including:
<ul>
<li><a class="negrito"
href="https://developer.mozilla.org/en-US/docs/Glossary/XHTML" target="_blank">XHTML</a></li>
<li><a
class="negrito" href="https://developer.mozilla.org/en-US/docs/Web/MathML" target="_blank">MathML</a></li>
<li><a class="negrito" href="https://developer.mozilla.org/en-US/docs/Web/SVG" target="_blank">SVG</a></li>
<li><a
class="negrito" href="https://developer.mozilla.org/en-US/docs/Glossary/RSS" target="_blank">RSS</a></li>
<li><a class="negrito" href="https://developer.mozilla.org/en-US/docs/Glossary/RDF"
target="_blank">RDF</a></li>
</ul>
You can also define your own.
</p>
</article>
</section>
</div>
<div id="section_structure_XML" class="section_structure_XML">
<section id="Structure_of_an_XML_document" class="main-section">
<header>
Structure of an XML document
</header>
<article>
<p>
The whole structure of XML and XML-based languages is built on <a class="negrito"
href="https://developer.mozilla.org/en-US/docs/Glossary/Tag" target="_blank">tags</a>.
</p>
</article>
<h1>XML declaration</h1>
<article>
<p>
XML - declaration is not a tag. It is used for the transmission of the meta-data of a document.
</p>
<p>
<code>HTML
<?xml version="1.0" encoding="UTF-8"?></code>
</p>
<h2>Attributes</h2>
<p>
<code>version</code>
</p>
<p>
Used version XML in this document.
</p>
<p>
<code>encoding</code>
</p>
<p>
Used encoding in this document.
</p>
<h2>Comments</h2>
<p>
<pre>
<code>HTML
<!-- Comment -->
</code>
</pre>
</p>
</article>
</section>
</div>
<div id="section_correct_XML" class="section_correct_XML">
<section id="Correct_XML_valid_and_well_formed" class="main-section">
<header>Correct XML valid and well formed</header>
<h1>Correct design rules</h1>
<article>
<p>For an XML document to be correct, the following conditions must be fulfilled:</p>
<ul>
<li>Document must be well-formed.</li>
<li>Document must conform to all XML syntax rules.</li>
<li>Document must conform to semantic rules, which are usually set in an XML schema or a DTD (<a
class="negrito" href="https://developer.mozilla.org/en-US/docs/Glossary/Doctype"
target="_blank">Document Type Definition<a>).</li>
</ul>
</article>
<h1>Example</h1>
<article>
<p>
<textarea name="" id="Cod22" cols="120" rows="8" disabled>
<?xml version="1.0" encoding="UTF-8"?>
<message>
<warning>
Hello World
<!--missing </warning> -->
</message>
</textarea>
</p>
<p>Now let's look at a corrected version of that same document:</p>
<textarea name="" id="Cod342" cols="120" rows="8" disabled>
<?xml version="1.0" encoding="UTF-8"?>
<message>
<warning>
Hello World
</warning>
</message>
</textarea>
</article>
<article>
<p>
A document that contains an undefined tag is invalid. For example, if we never defined the <b
id="code_alternativo"><warning></b> tag, the document above wouldn't be valid.
</p>
<p>
Most browsers offer a debugger that can identify poorly-formed XML documents.
</p>
</article>
</section>
</div>
<div id="section_entities" class="section_entities">
<section id="Entities" class="main-section">
<header>Entities</header>
<article>
<p>
Like HTML, XML offers methods (called entities) for referring to some special reserved characters (such
as a greater than sign which is used for tags). There are five of these characters that you should know:
</p>
</article>
<div class="container">
<div class="table-responsive">
<table class="table">
<thead>
<tr>
<th>Entity</th>
<th>Character</th>
<th>Description</th>
</tr>
</thead>
<tbody>
<tr>
<td>&lt;</td>
<td class="td_center"><</td>
<td>Less than sign</td>
</tr>
<tr>
<td>&gt;</td>
<td class="td_center">></td>
<td>Greater than sign</td>
</tr>
<tr>
<td>&amp;</td>
<td class="td_center">&</td>
<td>Ampersand</td>
</tr>
<tr>
<td>&quot;</td>
<td class="td_center">"</td>
<td>One double-quotation mark</td>
</tr>
<tr>
<td>&apos;</td>
<td class="td_center">'</td>
<td>One apostrophe (or single-quotation mark)</td>
</tr>
</tbody>
</table>
</div>
</div>
<article>
<p>
Even though there are only 5 declared entities, more can be added using the document's Document Type
Definition. For example, to create a new <b>&warning;</b> entity, you can do this:
</p>
<p>
<textarea readonly name="Cod_9" id="Cod_9" cols="120" rows="9" disabled>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE body [
<!ENTITY warning "Warning: Something bad happened... please refresh and try again.">
]>
<body>
<message> &warning; </message>
</body>
</textarea>
</p>
<p>
You can also use numeric character references to specify special characters; for example, <b
id="code_alternativo">&#xA9;</b> is the "©" symbol.
</p>
</article>
</section>
</div>
<div id="section_displaying_XML" class="section_displaying_XML">
<section id="Displaying_XML" class="main-section">
<header>Displaying XML</header>
<article>
<p>
XML is usually used for descriptive purposes, but there are ways to display XML data. If you don't
define a specific way for the XML to be rendered, the raw XML is displayed in the browser.
</p>
<p>
One way to style XML output is to specify CSS to apply to the document using the <b id="code_alternativo">xml-stylesheet</b>
processing instruction.
</p>
<code>XML
<?xml-stylesheet type="text/css" href="stylesheet.css"?>
</code>
<p>
There is also another more powerful way to display XML: the <b>Extensible Stylesheet Language
Transformations</b>(XSLT) which can be used to transform XML into other languages such as HTML. This
makes XML incredibly versatile.
</p>
<code>XML
<?xml-stylesheet type="text/xsl" href="transform.xsl"?>
</code>
</article>
</section>
</div>
<div id="section_recommendations" class="section_recommendations">
<section id="Recommendations" class="main-section">
<header>Recommendations</header>
<article>
<p>
This article is obviously only a very brief introduction to what XML is, with a few small examples and
references to get you started. For more details about XML, you should look around on the Web for more
in-depth articles.
</p>
<p>
Learning the HyperText Markup Language (HTML) will help you better understand XML.
</p>
</article>
</section>
</div>
<div id="section_see_also" class="section_see_also">
<section id="See_also" class="main-section">
<header>See also</header>
<ul>
<li><a href="https://www.xml.com/" class="external" target="_blank">XML.com</a></li>
<li><a href="https://www.w3.org/XML/" class="external" target="_blank">Extensible Markup Language (XML) @W3.org</a></li>
<li><a href="https://alistapart.com/article/usingxml/" class="external" target="_blank">Using XML: A List Apart</a></li>
<li><a href="https://google.com" class="external" target="_blank">Google</a></li>
<li><a href="https://aol.com" class="external" target="_blank">AOL</a></li>
</ul>
</section>
</div>
</div>
</main>
</div>
</div>
</body>
</html>
type or paste code here