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Re: CSS Transparent Background and 1.4.3?


From: Jim Homme
Date: Jan 24, 2017 10:17AM

From the below, I'm translating that the test is inclusive, and that to ensure a valid test, we should advise the developer to code an explicit background color. Is that accurate?



=========Jim Homme,
Team Lead and Accessibility Consultant,
Bender HighTest Accessibility Team
Bender Consulting Services, Inc.,

-----Original Message-----
From: WebAIM-Forum [mailto: <EMAIL REMOVED> ] On Behalf Of Patrick H. Lauke
Sent: Monday, January 23, 2017 7:19 PM
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).

Patrick H. Lauke

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