Intrinsically Responsive CSS Grid with minmax() and min()

CSS Grid is now widely supported across modern browsers, and there are lots of folks doing great work with it! But unfortunately, one of the most useful features of the specification doesn’t quite work as advertised. Specifically, it’s not possible to create an “intrinsically responsive grid” — that is, a grid that is responsive based on the size of its container — without the use of media queries. But thanks to some standards that are now available in some browsers and on their way to others, we can fix that!

Before I explain the solution, let’s review the problem. With CSS Grid, we can create a grid of items arranged in equally sized columns and tell those column sizes to adjust based on the amount of available space:

This technique uses a number of features in the Grid specification:

• repeat() tells Grid to create multiple tracks with the same size parameters (not necessarily the same size, though in this case they all end up being the same).

• auto-fill tells it to create as many tracks as necessary to fill the space.

• minmax(10rem, 1fr) tells it to determine each track’s size by finding a value between a minium of 10rem and a maximum of 1fr. The fr unit is what makes sure that the tracks are allowed to grow to fill any remaining space.

Thanks to all this, the container adds new columns as it grows. A key feature of this solution is that the columns change based on the container size, not the viewport size. That means we can apply this to a reusable component and be confident that it will always look right, without the need for media queries overriding the default behavior on specific pages. So what’s the problem?

Responsive... Sorta

Since each grid track has a minimum size of 10rem, they can’t shrink below that size. That means when the container is smaller than 10rem, the grid items overflow the container! To fix this, we’d have to wrap the grid-template-columns delcaration in a media query, like so:

But now that we’re in media query-land, our grid only switches when the viewport is small. We can’t put it inside a small container, or we run into the overflow problem all over again. This is why Heydon Pickering and Andy Bell’s Every Layout site generally avoids media queries and CSS Grid, instead achieving intrinsic responsiveness through Flexbox.

Thankfully, with some new additions to the CSS spec that have started landing in browsers, we can fix this issue, allowing CSS Grid to live up to its full potential as a tool for intrinsic web design.

The Intrinsically Responsive Grid

The previous example ran into problems because we were setting a fixed value as the minimum track size. When the container size shrunk, the items didn’t shrink with it, and thus: overflow. But what if we could set a minimum size that would shrink based on the container size, ensuring that our tracks were never too big for their container?

As luck would have it, we can do just that, with the help of the min() function:

ul {
  grid-template-columns: repeat(auto-fill, minmax(min(10rem, 100%), 1fr));
}

min() accepts one or more values and returns the smallest value. The magic of the function is that, just like calc(), the arguments can use different units, which allows us to return values that change dynamically based on context. In this case, we’re returning the current width of the container, capped at a maximum value of 10rem.

min() is one of three new comparison functions introduced as part of the CSS Values and Units Module Level 4. There’s also max(), which naturally does the inverse of min(). Finally clamp() is a convenience function that applies both a minimum and a maximum to a single value.

In this example, there are two cases we have to worry about, and min() solves for both of them. When the container is smaller than 10rem, the minimum value in our minmax() expression is set to the full width of the container, giving us a nice single-column view with no overflow. When the container is larger than 10rem, the minimum value is set to 10rem, so we get a responsive grid with equal tracks of at least 10rem each.

In the Real World

I know what you’re thinking. “This sounds cool and all, but I can’t actually use it yet.” You’re only half right.

min() isn’t very well supported, but it is available in at least one browser: Safari quietly implemented both min() and max() a few versions back! Unfortunately there’s no clamp() yet, but you can simulate it using the other two. Plus, Tab Atkins recently announced that Chrome support is on its way. If you want to keep track of browser support, CanIUse has a page for all three functions.

With that good news out of the way, here’s a working version of the code above (open in Safari to see it in action):

One browser isn’t great, but it doesn’t mean you have to give up on this solution. For now, you can layer it onto your existing code as a progressive enhancement. Here’s my preferred solution:

This one uses a calc() expression as a fallback. The key part is the calc(10% + 7.5rem), which combines a fixed minimum with a percentage width. By computing the minimum based on both of these, we lower the threshold for triggering overflow. Now it will trigger when the container is slightly larger than 7.5rem, whereas in our earlier solution it would trigger at 10rem. This solution is a bit finnicky though, so you’ll want to adjust both the percentage and fixed values to fit your grid’s design.

With this as our fallback, we can take advantage of CSS’s ability to override duplicate property declarations by re-declaring grid-template-columns. Browsers that support min(), namely Safari, will get the fully responsive solution, while Chrome, Firefox, Edge, and others will get the fallback. As more browsers add support for min(), they will automatically switch over to the new layout.

Wrapping Up

The min(), max(), and clamp() functions are really powerful tools, allowing us to toggle between values in real time based on changing conditions. Being able to test them out in a real browser opens up lots of opportunities for exploration, and I’m confident that this little fix for CSS Grid is just scratching the surface of the many ways that developers will use these features going forward.

This post was originally published on Evan Minto’s personal blog. Which, it turns out, is a great place to go if you’d like to hire Evan for a web development, design, or accessibility project!