Write Fewer Media Queries With the Clamp() CSS Function

Here's a neat little trick:

You can use the clamp() CSS function to make font-size responsive and fluid!

It works by "clamping", or restricting, a flexible value between a minimum and a maximum range.

Here's how to use it:

1. Choose a minimum value: E.g. 16px
2. Choose a maximum value: E.g. 34px
3. Choose a flexible value: E.g. 5vw

h1 {
  font-size: clamp(16px, 5vw, 34px);
}

In this example, the h1 font-size value will be 5% of the viewport width. But only if that value is bigger than 16px and smaller than 34px.

For instance, if your viewport width is 300px, your 5vw value will be equal to 15px. However, you clamped that font-size value to a minimum of 16px, so that is what is going to be.

On the other hand, if your viewport width is 1400px, you 5vw will be a whooping 70px! But luckily you clamped that maximum value to 34px, so it won't grow past that.

Oh, and it also works with padding! And margin!

And literally any other property that accepts a length, frequency, angle, time, percentage, number, or integer!

Browser support is also pretty good if you don't need to support IE/older Safari versions, look:

I love modern CSS. What are your thoughts on clamp()?

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EDIT: Be sure to check Darshak's suggestion in the comments if you need to add an alternative implementation for older Safari!

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Cover photo by Matt Artz on Unsplash

Thanks to Madza for the name of this series 😄

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Comments

[Darshak Parikh]

For older browsers, we could do something like:

h1 {
  font-size: 16px;
}

@supports (font-size: clamp(16px, 5vw, 34px)) {
  h1 {
    font-size: clamp(16px, 5vw, 34px);
  }
}

This should at least work on older Safari. As for IE, well, it doesn't support @supports. :|

[Vitor Paladini]

Great suggestion, Darshak! I wish I could pin comments

[Erick Eduardo Petrucelli]

Hey Vitor, you could edit the post adding this suggestion. Makes sense to increase support with little effort.

[Vitor Paladini]

Well, it's more a matter of graceful degradation than support increase but your idea is great, I'll do it right now!

[Jeremy Smith]

Awesome! Thank you for the article and the examples. Much appreciated!

Reading this reminded me of a Github project I saw a couple months ago that allows you to clamp "a line" of text so that the same number of words stay on it regardless of font size.

github.com/tvanc/lineclamp

[Clifton Long Jr.]

Dang, that's awesome.

It's wild seeing how CSS is evolving.

[Vitor Paladini]

Yeah! My first experiences with CSS were full of floats and clearfixes so I'm glad to have modern tools like CSS functions, custom properties and Flexbox now 🙂

[Mihail Malo]

Where it really shines is if you do something like

* {
  font-size: clamp(1rem, calc(5vw+0.8rem), 4rem)
}

so that you can modify the speed, and domain, of the responsive scaling.

[GlyphCat]

Damn, this is going to forever change the way I style my content.

[Peter Witham]

This is genius, never heard of clamp before now.
Thanks!

[👨🏾‍💻 Kam Banwait]

Hmmm, can this be pollyfilled in anyway?

EDIT: found a good solution to use it in older browsers via sass bronco.co.uk/our-ideas/creating-a-...

[Vitor Paladini]

The tricky part is that the browser also needs to support the vw. Which our old friend IE also doesn't and never will. :(

I believe the only way to polyfill it would be by using something with JS, like fittextjs.com/

[The_Keizzmann😁🎹🎹💻]

Thank you so much for sharing this

This will really improve my responsive designing skills

[Eugene Vedensky]

It's crazy how powerful these functions get when you mix them in with modern modules, too, like grid.

[Michał Murawski]

Damn! Some time ago I needed to implement this kind of thing. I only found JS libraries that did not meet my expectations. I wonder how would it have been with this feature :)

[Vitor Paladini]

I believe you're talking about fittextjs.com, right? I also had to do something similar in the past and got super bummed out with the fact that I had to use JS for such a small thing