Interpolating Numeric CSS Variables for a Responsive Web Design Experience

Interpolating Numeric CSS Variables

CSS variables, or custom properties, are a powerful tool for creating dynamic and reusable styles in your web projects. They are widely supported across modern web browsers, and can be accessed with JavaScript to create powerful dynamic themes. However, one limitation of CSS variables is that they can only store strings – not numbers. In this article, we’ll explore how to use CSS variables to create dynamic values for things like font sizes or lengths.

What Are CSS Variables?

CSS variables, also called custom properties, are pieces of data that can be assigned to an element or document. They can be used to store any type of value, from colors to font sizes to URLs. The syntax for defining a variable is very simple; you use the -- prefix followed by a name for the variable, and then a colon and the value that you want it to contain:

--my-variable: #777;

Once a variable is defined, you can use it anywhere in your style sheet by using the variable's name within the var() function:

div { color: var(--my-variable); }

Interpolating Values

As previously mentioned, CSS variables can only store strings – not numbers. This means that any attempt to store numeric values will result in those values being treated as strings. While this can be useful in certain cases – for example, setting font sizes – it can be difficult to interpolate numeric values between two points.

Fortunately, there is a way to interpolate numeric values in CSS variables. The trick is to wrap the variable in another function called calc(). This function allows you to perform arithmetic operations on the value stored in the variable. For example, if we want to create a variable that is the sum of two other variables, we could write:

--total-size: calc(var(--size-1) + var(--size-2));

We can also perform more complex operations like multiplication and division in the same manner. This allows us to create powerful dynamic themes that can be reused throughout our projects.

Conclusion

CSS variables are a great tool for creating dynamic and reusable styles. While they can only store strings, we can use the calc() function to interpolate numeric values. This allows us to create powerful dynamic themes that can be reused throughout our projects.