What are CSS variables: How they Work with example
CSS variables, also known as custom properties, are a powerful feature in CSS that allows you to define reusable values, such as colors, font sizes, or margins, and use them throughout your CSS code. CSS variables work similarly to variables in programming languages, allowing you to change the value in one place and have it updated across your code.
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Here we are sharing about
* How to declare a CSS variable
* How to use CSS variables in your code
* Inheritance with CSS variables
* fallback values with CSS variables
* the benefits of CSS variables
To declare a CSS variable, you use the -- prefix followed by the variable name, like this:
To declare a CSS variable, you use the -- prefix followed by the variable name, like this:
css example :
:root {
--main-color: #007bff;
}
This example declares a variable named --main- color with the value #007bff. The: root selector sets the variable to apply globally to the entire document, but you can also define variables on specific elements.
To use a CSS variable in your code, you use the var() function and pass in the name of the variable, like this:
CSS
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h1 {
color: var(--main-color);
}
This example sets the color of all h1 elements to the value of the --main-color variable. You can use CSS variables in any CSS property that accepts a value, including properties that are not typically customizable, like transform and box-shadow.
CSS variables follow the normal rules of CSS inheritance, meaning that a variable defined on a parent element will be inherited by its children. However, the value of a variable on a child element can be overridden by redefining the variable on the child element.
CSS variables also have a scope that is determined by the element that defines them. If a variable is defined on the : root element, it can be accessed anywhere in the document, but if it is defined on a specific element, it can only be accessed within that element and its children.
Fallback values can be used with CSS variables to provide a default value if the variable is undefined or the browser does not support CSS variables. You can use the var() function and pass in a second value that will be used as the fallback, like this:
css
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h1 {
color: var(--main-color, #333);
}
This example sets the color of all h1 elements to the value of the --main-color variable, but if the variable is undefined, it will default to color #333.
The benefits of CSS variables are numerous. They allow for more efficient and consistent code by making it easy to reuse values throughout your CSS code. They also make it easier to change the values of multiple properties at once, which can be especially useful for theming or responsive design. Additionally, they provide a way to create more maintainable code by reducing the amount of hardcoded values and making it easier to update styles across your codebase.
How to Declare a CSS Variable:
To declare a CSS variable, use the syntax "--variable-name: value;" with the desired variable name and value. For instance, the following code declares a variable named "--primary-color" with a value of "#007bff":
: root {
--primary-color: #007bff;
}
This approach is advantageous since you only need to change the value of the variable in one place to modify it throughout your code.
How to Use CSS Variables in Your Code:
To use CSS variables in your code, reference the variable name in place of the specific value. For instance, you can use the following code to apply the primary color variable to the background of an element:
background-color: var(--primary-color);
Inheritance with CSS Variables:
CSS variables support inheritance, which means that child elements can inherit the value of a variable declared in a parent element. For example, if you declare a variable in the body element, you can use that variable in any child element, and it will inherit its value.
Scope with CSS Variables:
CSS variables have a scope that depends on where they are defined. If you define a variable inside a selector block, that variable will only be available within that block. In contrast, defining a variable in the : root selector makes it globally available.
Fallback Values with CSS Variables:
Fallback values come in handy when you're using variables, and the browser doesn't support them. Fallback values provide a fallback value that can be used in case the browser doesn't support the variable. For instance, the following code defines a fallback value of "blue" for the variable "--primary-color":
background-color: var(--primary-color, blue);
The Benefits of CSS Variables:
>> CSS variables are advantageous for several reasons.
>> For one, they make it easier to maintain and update code by allowing you to modify a single variable value rather than changing it in multiple places.
>> Additionally, they improve the readability of code by making it easier to identify where a specific color or font value is used throughout the code.
>> CSS variables also support inheritance, scoping, and fallback values, which enhances their flexibility and versatility.
>> Finally, they improve the performance of websites by reducing the amount of code that needs to be loaded by the browser.
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