Using rem-based media queries

One of my favorite CSS "tricks" is the rem-based media query:

@media screen and (min-width: 48rem) {
  /*  Styles for tablets and above */

Instead of using pixels for the width of the screen, you can define the width of the screen using rem units. One key benefit to this is accessibility.

I often bump my font size up larger than the default. While I can see fine without it I find the larger font sizes relaxing on my eyes.

Writing media queries like this allows you to scale layout with a user's font-sizing preferences. So if your user has a tablet screen (~768px) and a 150% font size, they would see the mobile layout. This mobile layout is more helpful if your font is taking up a significant portion of your tablet-sized screen width.

Lastly, a couple caveats to this approach. First, if you're actually changing the font-size on the html element, this might not be for you. Personally, I've never had to actually change the root font-size dynamically so this is rarely a concern for me.

Second, rem-based media queries can take a while to get used to. You'll have to do some math if you need to figure out standard screen sizes. For example, 768px divided by a root font-size of 16 results in 48rem. That said, I think the benefits (accessibility) outweigh the cost (unfamiliarity).

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