Just recently on a Clearleft project, some of us were discussing whether there was a reason not to use
rems instead of
ems for media queries. Apart from one older browser implementation difference, we couldn’t come up with much.
Some in-depth research here supports the use of
em values for media queries. Very good to know.
A very handy tool for figuring out breakpoints for responsive images.
Upload an image in its largest size, play around with the settings, and then generate the breakpoints, the markup, and the resized images for each breakpoint.
I share the concerns expressed here about the “sizes” attribute that’s part of the new turbo-powered img element (or “the picture element and its associates”, if you prefer). Putting style or layout information into HTML smells bad.
This is a concern that Matt Wilcox has raised:
Change the design and those breakpoints are likely to be wrong. So you’ll need to change all of the client-side mark-up that references images.
I can give you a current use-case: right here on adactio.com, you can change the stylesheet …so I can’t embed breakpoints or sizes into my img elements because—quite rightly—there’s a separation between the structural HTML layer and the presentational CSS layer.
Vasilis examines the multitude of factors that could influence an ideal measure.
Another call for design-based (rather than device-based) breakpoints in responsive sites.
Another plea for content-out rather than canvas-in design.