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RE: Viewport Units for font sizes

From: Jonathan Avila <jon.avila@ssbbartgroup.com>
Date: Tue, 14 Apr 2015 17:32:01 +0000
To: Eric Eggert <ee@w3.org>, WCAG <w3c-wai-gl@w3.org>
Message-ID: <BY2PR03MB272B83C825D343AD15156BE9BE60@BY2PR03MB272.namprd03.prod.outlook.com>
Eric, thanks for sharing this.  I’d consider it a violation under SC 1.4.4.  Even with zoom text-only in Firefox the text still doesn’t enlarge.  IMO even if it is a user agent behavior issue it’s not accessibility supported.  So, this appears to be a failure we should document.

Best Regards,


Jonathan Avila
Chief Accessibility Officer
Phone 703.637.8957
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From: Eric Eggert [mailto:ee@w3.org]
Sent: Tuesday, April 14, 2015 10:21 AM
Subject: Viewport Units for font sizes

Hi all,

as it looks[1], viewport units for font-sizes would be great for responsive web design but apparently are not accessible at all because they are defined as fixed measurements – almost like pixels. And as the viewport is getting smaller when you zoom in, the calculated font size stays the same.

Take a look at this example and try to scale it in a browser that supports viewport units[2]:


I wonder if people are aware of this and if we might to add a failure technique. I also wonder if we may be able to turn the car around and work out an implementation with CSS WG that allows implementation… (I don’t know if there is a solution that removes the main benefit for people using low vision that they can get the mobile view on a desktop and don’t need to scroll horizontally, if properly implemented.)

Best, Eric

[1] https://twitter.com/SaraSoueidan/status/587694001500872704

[2] http://caniuse.com/#feat=viewport-units


Eric Eggert
Web Accessibility Specialist
Web Accessibility Initiative (WAI) at Wold Wide Web Consortium (W3C)
Received on Tuesday, 14 April 2015 17:32:32 UTC

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