3. Selectors in CSS

What are CSS Selectors?

CSS selectors allow us to choose specific elements and apply styles to them. Suppose we want to add a custom style to only a specific tag(s). There, We can make use of CSS selector.

Types of selectors

There are different types of CSS selectors:

Note:- There is also Attribute Selector.

Universal Selector

Universal selector represented by "*" targets all the HTML elements on the page.
The syntax of Universal Selector is as follows:

* {
    property : value;
}

Consider the code snippet:

<html>

<head>
    <style>
        * {
            color: purple;
            text-align: center;
        }
    </style>
</head>

<body>
    <p>Welcome to </p>
    <h1>CodeWithHarry</h1>
</body>

</html>

Output:

Notice, Irrespective of the tag, the style will be applied to all the elements and tags.

Element Selector (Type Selector)

The element selector selects the target element based on the specific type.
Suppose you want to underline all the <p> tags; in this case, the element selector will be the best choice.
The syntax of Element Selector is as follows:
- selector can be any HTML tag. Here, we have considered the p tag.

p {
    property : value;
}

Consider the code snippet:

<html>

<head>
    <title>CSS</title>
    <style>
        p{
            text-decoration: underline;
        }
    </style>
</head>

<body>
    <h1>CodeWithHarry</h1>
    <h2>we offer: </h2>
    <p>Python Tutorials - 100 Days of Code</p>
    <p>Ultimate JavaScript Course</p>
    <p>React JS Tutorials For Beginners</p>
</body>

</html>

Output:

Note: Element selector is not recommended as the same tag can be used multiple times in the document. So, overlapping rules can occur in the stylesheet.

ID Selector

The ID selector targets the elements based on the specific ID.
It is written with the hash “#” character followed by the ID name in the style sheet.
The syntax of ID Selector is as follows:

[[ID]] {
    property : value;
}

Consider the code snippet:

<html>
<head>
    <style>
        [[title]] {
            text-align: center;
            color: red;
        }
    </style>
</head>

<body>
    <h1 id="title">CodeWithHarry</h1>
    <p>I'm a Developer and the founder of CodeWithHarry.com</p>
</body>

</html>

In the style block, the selector #title, will only target the HTML element having an ID of "title".

Consider the output of the above code:

Notice, how the property color: red is only applied to <h1> tag.

Class Selector

The class selector does the same job as the id selector, a class selector helps group various types of elements.
Suppose, we want to give a custom style to a specific group of elements. In this case, the class selector is the best option.
It is written with the period “**.**” character followed by the class name in the style sheet.
The syntax of Class Selector is as follows:

.class {
    property : value;
}

Consider the code snippet:

<html>

<head>
    <title>CSS</title>
    <style>
        .red {
            color: red;
        }
    </style>
</head>

<body>
    <p>This is simple p tag</p>
    <p class="red">This p tag has class red</p>
    <p>This is simple p tag</p>
    <p class="red">This p tag has class red</p>
</body>

</html>

In the above code snippet, the color:red will only be applied to the element having class 'red'.

Note: The class selector helps in grouping two or more elements.

Group Selector

The group selector is used to minimise the code.
Commas "," are used to separate each selector in a grouping. This reduces the number of lines of code. The code also looks clean.

The syntax of Group Selector is as follows:

div, p, a {
    property : value;
}

Consider the code snippet:

<html>

<head>
    <title>CSS</title>
    <style>
        h1 {
            color: red;
        }

        p,a {
            color: purple;
        }
    </style>
</head>

<body>
    <h1>CodeWithHarry</h1>
    <p>This is the p tag</p>
    <a href="#">This is the anchor (a) tag</a>
</body>

</html>

In the <style> block, p and a tag are grouped together so, that both tags will have the same properties.

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Attribute Selector

The [attribute] selector is used to select elements with a specified attribute.

Syntax:-

 element[attribute] {
  background-color: yellow;
}

Example:-

a[href="youtube.com"] {
 color: blue;
}
/* all <a> tag with YouTube.com link will be blue */

Summary:

Universal Selector(*): Target the entire page.
Element Selector: Target a specific element.
ID Selector(#): Target element with a specific ID.
Class Selector(.): Tar
get element(s) with the same class.
Group Selector: Group elements and target them.