Wikipedia:Colour contrast

because it has blue text on a blue background.

Text that you probably can read, such as red on green, may present a similar problem to people who have colour-blindness.

Text with low contrast, such as light grey on dark grey, presents a similar problem to people with other eyesight-related conditions.

The more severe their condition, the higher the contrast has to be for them to be able to read it.

Our non discrimination policy is

It says: .

To avoid these problems, you should ensure that text meets the guidelines set out in WP:COLOUR.

Snook's Colour Contrast Check provides a comprehensive check of whether a particular choice of foreground and background colours meets WCAG 2.0 standards for brightness difference, colour difference and contrast ratio (and at what level – AAA should be met unless there are very good reasons not to).

You can find the text colour and background colour as a hexadecimal value by using the "Inspect element" function that most modern browsers provide. The default colour for blue-linked text with the Vector skin is #0645AD (    ) and for visited links is #0B0080 (    ). Both should always be checked in addition to black (#000000) against any proposed background colour in case links are added later.

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Wikipedia