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Tag: color contrast

Ultimate checklist for making your plugin accessible

HTML code semantics

Following HTML code semantics is fundamental in making your web applications accessible because assistive technologies, like screen readers, rely on the code to transmit the correct information to the user.

Forms are communly inaccurate due to a lack of the label tag or the misuse of the input fields.(Check out the W3C for forms in HTML4 or W3C for forms in HTML5.)

Another commun mistakes involves data tables weither by not structuring your table with the proper elements or  by adding visual attributes that should go in the CSS, (Check out W3C for tables in HTML4 or W3C for tables in HTML5.)

Follow W3C standards to the letter and you will have a good start.

Use CSS

To keep the integrity of your code separate content from presentation. In the case of a data table, attributes like cellspacing and cellpadding should be replaced by padding of the td element in your css file. This will allow users to strip down the visuals to suit their own needs.

Tabbed Navigation

Many users use only the tab key to navigate within a web browser and webpage, because they cannot use a mouse (in case of limited motor skills or blindness).

Colour contrast

There are many tools to help you choose the appropriate colour contrasts between background and foreground of your text.

A proper ratio of luminosity assures that users with visibility issues can clearly see differences between elements. Think of users with colourblindness or eye sensitivity.

WAI-ARIA attributes

If you want to go a step further and you are coding in HTML5, you can use ARIA attributes to compliment all previous steps. WAI-ARIA is a set of elements that give extra code information to assistive technologies.

More information about ARIA:

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Top Accessible WordPress themes

This assessment is very simplistic and constitutes a basic preliminary review. It is not comprehensive nor exhaustive.

I chose themes from the Free Theme Directory and searched for Web Accessible and Accessibility. I narrowed my selection by considering which theme would be easily customizable, have good contrast between foreground and background, have elements in a convenient location and be aesthetically pleasing as is.

I then used the plugin Demo Data Creator to generate more content for posts, pages, comments and categories.

The following themes made the cut:

Precious version 4.0.1
At first glance the layout is pretty simple and effective. Convenient breadcrumb on top of page. Upon disabling the style sheets, nothing is out of order. Validates for XHTML 1.0 Transitional and CSS2.

Stardust version 2.7
Very stylish out of the box with flexible width. Has “Skip to content” and “Skip to menu” without CSS. By disabling the images, the date for each post is too dark. Validates for XHTML 1.0 Strict, but not in CSS with 6 CSS2 errors.

Whitepress version 1.1.7
This theme includes a skip to content, navigation and search form when disabling CSS. Has a nice javascript for going through the sidebar items, but also works when javascript is disabled. Uses fixed width for 1024×768 resolution. Validates for XHTML 1.0 Strict, but not in CSS with 1 CSS2 error.

Dodo version 1.2.1
This theme is what this website is based on. The color of the posts date and other meta information is also too light. By disabling the images, the text of the main menu has not enough contrast with its background. With a little tweek here and there, it’s really nice. Fails to validate with XHTML 1.0 Strict with 1 error, but passes CSS2.

Precious and Stardust passed the Firefox Accessibility Extension 1.5.61.0 rule set with only warnings signaled .The themes Whitepress (2 Fails) and Dodo (1 Fail) did not pass.

For validation, I used Markup Validation Service and The W3C CSS Validation Service.

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Check My Colours

www.checkmycolours.com is a website for you to easily check if the colours on your website are accessible.

This tool takes all of the references to colour from your web page including your CSS and nicely compares the background colours to the foreground colours. The report that gets tabulated shows very bluntly what instance is acceptable and what instance is not. The system analyses three things: Contrast Ratio, Brightness difference, and Color difference. By clicking on the rows, it also allows the user to find another colour that would replace the current one. Unfortunately, this feature is a little hard to click on.

The site can give the user an idea of what is lacking in terms of colour accessibility, but does not offer a comprehensive understanding of what the guidelines are. Explaining what the categories and the numbers mean might clarify the systems results.

Let me demystify it for you.

Contrast Ratio: Contrast is measured using a formula that gives a ratio ranging from 1:1 (no contrast) to 21:1 (maximum contrast). AA and AAA refers to the level of priority. Level AA are strongly recommended (mininum contrast is 4.5:1) to allow most users accessibility. Level AAA are suggested (mininum contrast is 7:1) to allow some users accessibility.

Algorithm for luminosity contrast ratio in Web Content Accessibility Guidelines 2.0 Glossary.

Brightness difference: Another formula that evaluates the difference between the background brightness, and the foreground brightness. This should be greater than 125.

Color difference: This formula refers to the difference between the background colour and the foreground colour  and should be greater than 500.

Formulas are explained in the document Techniques For Accessibility Evaluation And Repair Tools.

The limitation of these types of applications is that we cannot check the colour balance from images.  This is one of the reasons that it is not recommended to make any text into images. They cannot be viewed by external reading programs.

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Color Contrast Analyser by Colors on the Web

I have been using this tool for some time now. It’s simple and straight forward. It will tell you if your colour combinations are good or not.  Large and bolded text are categorized differently than smaller text. The program also tells you what priority your combination represents. Priority 3 (AAA) is the lowest level, so for all intents and purposes, this is the minimum requirements. Although the page is a little clutered for my liking, I bare it. After all it’s free!

Check it out at: http://www.colorsontheweb.com/colorcontrast.asp

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