How to Conditionally Set Font Size in CSS: The Power of CSS Variables

Learn how to easily conditionally set the font size of an element in CSS, only if its parent's font size is not explicitly defined.
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How to Conditionally Set Font Size in CSS: The Power of CSS Variables

When creating web pages, one of the frequent challenges developers face is managing font sizes effectively, especially when it comes to different parent elements. Have you ever wondered how to set the font size of a child element only if its parent doesn’t have an explicit font size defined?

In this guide, we will explore how to conditionally set the font size of an element by utilizing CSS variables. This approach can help maintain a clean and dynamic styling system for your site.

The Problem

You have a structure as follows:

[[See Video to Reveal this Text or Code Snippet]]

You want to ensure that the <p> element's font size gets set to 14px, but only when the <div> element doesn’t have a specific font size defined (meaning it’s using font-size: inherit).

This might appear simple at first, but it requires a nuanced solution. If the <div> has a font size defined, you want the <p> to inherit it. If it doesn’t, default to 14px.

The Solution: Using CSS Variables

One effective method to achieve this is through the clever use of CSS variables. Here’s how you can implement it.

Step-by-Step Implementation

Define a CSS variable for the font size in the parent <div>.

Set the font size for the <p> in a way that it will fallback to 14px if the parent's variable is not set.

Example Code

You can implement the solution like this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code:

The first rule sets the font size of the <div> using a CSS variable named --f.

The second rule for the <p> element uses the same variable. If --f is defined (such as 20px), the <p> will have the same font size. If not, it will default to 14px.

Complete HTML Example

Here is how you can put this all together:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By utilizing CSS variables, you can effortlessly manage conditional font sizes in your CSS. This provides flexibility in your design while keeping your code clear and maintainable.

Explore using CSS variables in other areas of your projects for more dynamic styling options. Happy coding!