CSS Custom Selectors
Custom Selectors, also known as CSS variables, offer flexibility and maintainability in styling web pages. They allow us to define our own selectors and reuse them throughout our stylesheets. This makes our CSS more modular and easier to manage.
Introduction to Custom Selectors
Basic Syntax
The syntax for defining a custom selector is straightforward
:root {
--custom-selector: value;
}
Here, --custom-selector is the name of our custom selector, and value is the value associated with it.
Let’s see an example
:root {
--main-color: #007bff; /* Defining a custom selector for main color */
}
How to Use Custom Selectors
Once defined, we can use custom selectors anywhere within our CSS code by referencing them using the var() function
.selector {
color: var(--main-color); /* Using the custom selector */
}
Example Output
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>CSS Custom Selectors Example</title><style>:root {
--main-color: #007bff; /* Defining a custom selector for main color */
}
.selector {
color: var(--main-color); /* Using the custom selector */
}</style></head>
<body>
<div class="selector">
This text should be colored with the main color.
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</html>
Explanation
In this example, we define a custom selector --main-color with the value #007bff. Then, we use this custom selector within the .selector class to set the text color.
Output: The text inside the .selector class will be colored with the main color #007bff.
Advanced Usage of Custom Selectors
Custom Selectors offer more than just simple variable substitution. Let’s explore some advanced techniques
Using Custom Selectors in Media Queries
We can use custom selectors within media queries to make our styles adapt to different screen sizes
@media (max-width: 768px) {
.selector {
font-size: var(--small-font-size);
}
}
Nesting Custom Selectors
Custom selectors can be nested within other selectors, allowing for more complex styling
.parent {
--text-color: red;
}
.child {
color: var(--text-color);
}
Manipulating Custom Selectors with JavaScript
JavaScript can be used to dynamically manipulate custom selectors, providing even greater flexibility
document.documentElement.style.setProperty('--main-color', '#ff0000');
Practical Examples
Let’s dive into some practical examples to solidify our understanding
Example 1: Theming
Custom selectors are excellent for theming. Let’s create a light and dark theme
:root {
--main-background: #fff;
--main-text-color: #333;
}
.dark-theme {
--main-background: #333;
--main-text-color: #fff;
}
body {
background-color: var(--main-background);
color: var(--main-text-color);
}
Example 2: Responsive Typography
Custom selectors can simplify responsive typography
:root {
--base-font-size: 16px;
}
@media (min-width: 768px) {
:root {
--base-font-size: 18px;
}
}
body {
font-size: var(--base-font-size);
}
Example Output
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>CSS Custom Selectors Practical Examples</title><style>/* Example 1: Theming */
:root {
--main-background: #fff;
--main-text-color: #333;
}
.dark-theme {
--main-background: #333;
--main-text-color: #fff;
}
body {
background-color: var(--main-background);
color: var(--main-text-color);
}
/* Example 2: Responsive Typography */
:root {
--base-font-size: 16px;
}
@media (min-width: 768px) {
:root {
--base-font-size: 18px;
}
}
body {
font-size: var(--base-font-size);
}</style></head>
<body>
<h1>Theming Example</h1>
<p class="dark-theme">This text is styled differently for a dark theme.</p>
<h1>Responsive Typography Example</h1>
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Explanation
- Example 1 demonstrates how custom selectors can be used for theming, allowing easy switching between light and dark themes.
- Example 2 showcases the usage of custom selectors for responsive typography, where font size adjusts based on viewport width.
Output: The HTML document will display examples of theming and responsive typography using custom selectors.
In this chapter, we've covered everything from the basics to advanced techniques of CSS Custom Selectors. By understanding and utilizing custom selectors effectively, you can write cleaner, more maintainable, and flexible CSS code for their web projects. Happy coding! ❤️