RE: px vs em vs rem

Amy, to answer your question about percent versus em -- percent based containers will allow for fluid layouts which will assist in making the site responsive.   Ems are good for scaling but they don't provide fluid layouts.   Many people with low vision find horizontal scrolling problematic.  Fluid layouts solve that issue and allow the text to become larger without requiring horizontal scrolling.

Jonathan

Jonathan Avila
Chief Accessibility Officer
SSB BART Group
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From: Carney, Amy L (EED) [mailto:amy.carney@alaska.gov]
Sent: Thursday, August 04, 2016 12:34 PM
To: w3c-wai-ig@w3.org
Subject: px vs em vs rem

Hi, all,

I recently watched a web accessibility video on Lynda.com that sparked a conversation about which units of measurement in CSS create a more accessible page for people with disabilities, such as visually impaired users.

What the tutorial taught was that fixed layout is the least accessible versus fluid layout which is the most accessible. But it didn't cite any sources, nor specify if that pertained to font-size, margin, padding, width, etc. And I'm having a hard time finding anything other than opinions online that specifically refer to this. Are px, ems, or rems really any better than one or the other when it comes to accessibility? Or have browser and assistive technology updates changed drastically enough that this isn't really an issue?

I'm still breaking into web development, so any suggestions or references for best practice would be much appreciated. Thank you!


Amy Carney
Publications Specialist II
Alaska State Libraries, Archives, and Museums
907.465.1313
amy.carney@alaska.gov<mailto:amy.carney@alaska.gov>