Milan Smudja: CSS ID Explained

In CSS, an ID selector is used to target a specific HTML element based on its unique identifier. An ID is a unique identifier assigned to an HTML element using the id attribute.

IDs should be used sparingly and only for elements that require unique styling or functionality. It's best practice to use classes instead of IDs whenever possible, since classes can be reused on multiple elements and are more flexible. IDs should only be used when a specific element needs to be targeted in JavaScript or when there is a unique style or behavior that needs to be applied to a single element.


<!DOCTYPE html>

<html>
<head><title>Title</title></head>

<link rel="stylesheet" type="text/css" href="mystyle.css">

<body>

<h2 id="level_A">Heading Level 2 - A</h2>

<h2 id="level_B">Heading Level 2 - B</h2>

<h2 id="level_C">Heading Level 2 - C</h2>

</body>
</html>

Explanations:

<link rel="stylesheet" type="text/css" href="mystyle.css">

This line is an HTML tag that links to an external CSS file named "mystyle.css" and is placed inside the head section of an HTML document.

<link> is an HTML tag that is used to link an external resource to an HTML document. In this case, we're linking to a stylesheet.
rel="stylesheet" specifies the relationship between the HTML document and the linked resource. In this case, we're specifying that the linked resource is a stylesheet.
type="text/css" specifies the type of the linked resource, which is a stylesheet in this case.
href="mystyle.css" specifies the path or URL to the external CSS file that we want to link to. The href attribute should point to the correct location of the CSS file on the web server or in the same directory as the HTML file.

Overall, this line of code is linking an external stylesheet to the HTML document and allowing it to be used for styling the content of the HTML page.

<link rel="stylesheet" type="text/css" href="mystyle.css">: This tag links to an external CSS file called mystyle.css. This file contains CSS rules that can be applied to the HTML elements on the web page.
<h2 id="level_A">Heading Level 2 - A</h2>: This tag defines a level 2 heading with the text "Heading Level 2 - A". The id attribute is used to give the element a unique identifier that can be targeted by CSS rules.
<h2 id="level_B">Heading Level 2 - B</h2>: This tag defines another level 2 heading with the text "Heading Level 2 - B". It also has a unique id attribute.
<h2 id="level_C">Heading Level 2 - C</h2>: This tag defines a third level 2 heading with the text "Heading Level 2 - C". It also has a unique id attribute.

With the id attributes added to the headings, the web page can now be styled using CSS rules that target those specific elements.


#level_A {
	background: yellow;
	color: navy;	
}

#level_B {
	background: lightblue;
	color: red;	
}

#level_C {
	background: green;
	color: yellow;	
}

In the given code, the CSS selectors use ID selectors to target specific HTML elements. The ID selector is indicated by the hash symbol (#) followed by the ID name.

The first CSS selector "#level_A" targets the h2 element with the ID "level_A" and sets the background color to yellow and the text color to navy.
The second CSS selector "#level_B" targets the h2 element with the ID "level_B" and sets the background color to light blue and the text color to red.
The third CSS selector "#level_C" targets the h2 element with the ID "level_C" and sets the background color to green and the text color to yellow.

So, this code will apply different background colors and text colors to the three h2 elements based on their unique IDs.

Using CSS from an external file is considered a smart idea for several reasons:

Separation of concerns: CSS is responsible for the presentation or styling of web pages. By separating CSS code into an external file, it is easier to maintain and manage the design and layout of the website separately from the content.
Consistency: An external CSS file can be linked to multiple HTML pages. By using the same external file, it ensures consistency in the design and layout of all web pages that use that CSS file.
Faster loading: External CSS files are cached by the browser, meaning that they don't need to be loaded every time a user visits a new page on the website. This can result in faster loading times for subsequent page views, improving the user experience.
Easier editing: By keeping CSS code in a separate file, it is easier to make changes and updates to the design and layout of the website. It is also easier to collaborate with other developers who may be working on the same project.

Using CSS from an external file promotes better organization, consistency, faster loading times, and easier maintenance and collaboration in web development.

Milan Smudja

Sunday, April 20, 2025

CSS ID Explained

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