Useful CSS Functions for Responsive Design

Sam Hilliard

When creating responsive websites, we often think of creating media queries with breakpoints that fit the most popular desktop, mobile, and tablet screen sizes. However, with the huge variety of devices out there, simply writing a few media queries. Moreover, (in my opinion) media queries are messy and cause code readability and extendability to suffer the more you write. Thus, I think they should be avoided whenever possible.

Luckily, modern CSS functions allow us to create responsive elements without using media queries. So, without further-a-do, here are a few life-saving CSS functions that will make your responsive designs cleaner and more flexible.

1. min()

Number one on the list is the min() function. This function accepts two (or more) parameters and returns the value of the parameter that is the smallest (pretty self-explanatory, right?).

While simple in design, its uses can be pretty powerful.

For example, it can turn this two-liner:

div {
    width: 100vw;
    max-width: 1000px;
}

into this:

div {
    width: min(1000px, 100vw);
}

Even though this is a simple (and common) use case, min() is not only limited to widths and heights but paddings, margins, and font sizes as well!

You can also pass in calculations without having to call the calc() function like this:

div {
    padding: min(25px, 10vh + 1rem);
}

2. max()

min()‘s opposite, max() functions in exactly the same way, except it returns the maximum value of its passed parameters.

Whereas the min() function is useful for limiting the growth of an element, the max() function can be used to limit the shrinking of an element.

div {
    padding: max(1rem, 3vh + 1rem);
}

In the preceding example, a div is created whose padding will grow depending on the viewport height but will not shrink past 1rem. This is great if you want to avoid responsive units from squishing your elements too much.

3. clamp()

The last function, clamp(), takes the best of both worlds from the previous functions. It bounds a value between a minimum and a maximum.

The syntax is as follows:

clamp(<minimum>, <base>, <maximum>)

Where clamp() is most useful for creating responsive font scales.

Take this example:

body {
    font-size: clamp(1rem, calc(1rem + 0.25vw), 1.25rem);
}

This creates a body font that gets no smaller than 1rem but never exceeds 1.25rem as the viewport width increases.

It’s kind of complex to come up with a responsive type-scale on your own, so here’s a super handy generator to make things way easier.

And that’s a wrap on these simple but powerful functions. I highly encourage you to use them whenever you can to make your code better and more responsive.

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