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Re: CSS Transparent Background and 1.4.3?

for

From: Jonathan Avila
Date: Jan 24, 2017 11:47AM


> - users *may* have specified that their browser should use specific custom default colours. For this reason, not specifying at least an explicit colour for the body/html elements in addition to a foreground colour would lead to the explicitly defined foreground colour being displayed over any kind of colour - making this impossible to test for conclusively since it will depend on the user's settings (unless your evaluation explicitly mentions that the result is only valid for default browser values).

This is why we have F24: Failure of Success Criterion 1.4.3, 1.4.6 and 1.4.8 due to specifying foreground colors without specifying background colors or vice versa (https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html)

Jonathan

Jonathan Avila
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-----Original Message-----
From: WebAIM-Forum [mailto: <EMAIL REMOVED> ] On Behalf Of Patrick H. Lauke
Sent: Monday, January 23, 2017 7:19 PM
To: <EMAIL REMOVED>
Subject: Re: [WebAIM] CSS Transparent Background and 1.4.3?

On 23/01/2017 18:28, Jim Homme wrote:
> Hi, According to what I just read, transparent is the default if a CSS
> background color isn't coded by the developer. Since I'm totally
> blind,, how does that affect testing for 1.4.3, contrast? For
> instance, are the results different for black text on a white
> background, specifically coded, than they are if the developer just
> specifies black text and allows the default to take over?

Assuming you mean a developer doesn't set explicit background color anywhere, including the body/html elements:

- browsers used to default to a medium/light grey colour as the default; however, most (all?) browsers these days default to a white default for the body/html

- users *may* have specified that their browser should use specific custom default colours. For this reason, not specifying at least an explicit colour for the body/html elements in addition to a foreground colour would lead to the explicitly defined foreground colour being displayed over any kind of colour - making this impossible to test for conclusively since it will depend on the user's settings (unless your evaluation explicitly mentions that the result is only valid for default browser values).

P
--
Patrick H. Lauke

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