Re: Minimum font size requirement or guideline for accessbility

Hello everybody

I agree with Guy. 16px is a reasonable size.

Guy did'nt say, how to get there. I guess he also uses em or rem to define th font size, but ex and ch are also scalable and there is no much difference in the usage, when it comes to multiplication (which you use for font size calculations usually). But there should be a difference in addition.


<https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units>
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CSS values and units - Learn web development | MDN<https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units>
developer.mozilla.org<https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units>

But I don’t think, you wanted to dive so deeply into the „a pixel is not a pixel“ debate, as this topic on the one hand is to wide for a mailing list contribution and on the other hand there is in depth information in the web since (at least) 2012 https://fronteers.nl/congres/2012/sessions/a-pixel-is-not-a-pixel-peter-paul-koch.


Anyway I'd like to add a warning: while all font-size based units ((r)em, ch, ex) work well for dimensions, breakpoints and so on, this ist not true for „proportional“ sizes like % - its proportional to container dimensions when used to define height and/or width, but not proportional to the font size of the parent element.

So in a content first approach they %, vh, vw, max, min… are not very helpful for container dimensions. Also breakpoints should not consider, if boxes fit into each other, but if the content chunks in the boxes still fit next to each other and make sense on small screens and when using zoom factors not equal to 1 - they may be even smaller than 1!

So what I wanted to say with so much words: I agree to Patrick. There are many variables attached to font sizes (don't let me start with custom properties using the cascade) and dimensions - to much for a general answer beyond „16px should be good“.

All this doesn’t matter for users anyway. They just need a reasonable size of 16px and the possibility to zoom in and out.

Marc


Am 08.03.2023 um 14:12 schrieb David Woolley <forums@david-woolley.me.uk>:

On 08/03/2023 12:33, richard userite wrote:
absolute measurements such as pixels

As I understand it, pixel long ago ceased to mean pixel and now means 1/96th of an inch.

proportional sizes such as "%" or "pt"

"pt" is, as far as I know, still a typographer's point, which is as absolute as "px", but using 72, rather than 96, as the divisor. Did you mean "em"?