Question
Answer and Explanation
You can't directly access or "inherit" CSS variables from one class to another in the way you might with programming variables. CSS variables (custom properties) are scoped to the element they are defined on and its descendants. However, there are several ways to achieve a similar effect of sharing or reusing values across different CSS classes.
Here are the primary methods:
1. Define Variables on a Common Ancestor:
- The most common and recommended approach is to define your CSS variables on a common ancestor element, such as :root (which targets the <html> element) or a specific container element. This makes the variables accessible to all descendants of that element.
- Example:
:root {
--main-color: blue;
--font-size: 16px;
}
.class-a {
color: var(--main-color);
font-size: var(--font-size);
}
.class-b {
background-color: var(--main-color);
font-size: var(--font-size);
}
- In this example, both .class-a and .class-b can use the --main-color and --font-size variables defined in :root.
2. Define Variables on a Specific Container:
- If you need variables to be specific to a section of your page, define them on a container element that wraps that section. This limits the scope of the variables.
- Example:
.container {
--section-color: green;
}
.container .class-c {
color: var(--section-color);
}
.container .class-d {
border-color: var(--section-color);
}
- Here, .class-c and .class-d can use --section-color because they are descendants of .container.
3. Using the `var()` Function:
- The var() function is how you access CSS variables. It takes the variable name as an argument (e.g., var(--my-variable)). You can also provide a fallback value if the variable is not defined (e.g., var(--my-variable, red)).
4. Avoid Direct Class-to-Class Variable Access:
- You cannot directly access a variable defined within a specific class from another class without using the methods described above. CSS variables are not designed for this kind of direct class-to-class interaction.
In summary, the best practice is to define your CSS variables on a common ancestor element (like :root) or a specific container element, and then use the var() function to access them in your different CSS classes. This approach promotes reusability and maintainability in your stylesheets.