Notes about Web Accessibility – Part 3

Status: Work in progress.
Last update: June 24, 2015

Lesson 3: Never rely only on color or images!

Web pages shall be designed so that all the information conveyed with color is also available without it.

Bad use of color examples:

  • Mark required fields on a form with red color.
  • Refers to a button only by it’s color “Click on the green button to continue”
  • Include text content on an image

How to use color on text elements:

The default contrast ratio of text and background has to be at least 5:1

Large scale text can allow a contrast ratio of at least 3:1 (18 point text or 14 point bold text is judged to be large enough to require a lower contrast ratio).

Incidental text, (text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content) or logotypes has no minimum contrast requirement.

Tools to check contrast ratio:

Lesson 3.1: Design and build web pages in a way that users can change the size of the text

  • Allow text to flow naturally at larger sizes.
  • Avoid defining text size in explicit units, like pixels or points, use relative values instead.
  • Again, don’t text inside of images. Use text!
  • You can add an “Adjust font size widget”.
  • Avoid moving, scrolling or flashing text. It could be extremely difficult to read.

Notes about Web Accessibility- Part 2

Status: Work in progress.
Last update: June 18, 2015

Lesson 2: Navigation

Rule: A method shall be provide that permits the user to skip repetitive navigation links. Specially when navigation is repeated in all pages or included in a page template.

User goal: Navigate to relevant content.


  1. Include a links that allow the user to skip over the navigation and go straight to the main content in the page.
    These links can be visible or invisible for non-disable users.
    Example: “Jump to main content” or “Skip navigation”
  2. Use HTML Headings properly. Screen readers and some browsers allow users to move from heading to heading announcing the headings at the corresponding level (h1, h2, h3, h4, h5).

Some options of how to implement this:

  • Text link at the top (visible)
  • Text link positioned off the screen and move it in on focus
  • Use tiny image links (1x1px) of the same color of the background
  • Use text links of the same color of the background

Alert! Do not use display: none to hide navigation links. Screen readers respect display: none interpreting it to mean don’t display in any medium including speech.

TIPS: How to improve your navigation links (or any kind of links)

  1. Choose wording on your links so the user can understand what the link will do.
  2. Organize your content using true headings (h1, h2, h3, h4, h5) and lists.
  3. Make sure content is well structure and clearly written. Check spelling, grammar and readability.

Notes about Web Accessibility – Part 1

I’m studying about Accessibility standards and best practices for the web. I decided to share my notes here, I hope you find them useful and we can improve the web together.

Status: Work in progress.
Last update: June 17, 2015

Lesson 1: Add AlternativesText for Images. 

Alternative text  is a text equivalent for a non-text element on the page.

Add alt attribute to images and input type=”image”


<img src=”mydog.jg” alt=”My dog” />
<input alt=”Submit” src=”img-submitbutton.jpg” type=”image” />

When an image is not a link, and carries no information or is redundant, use null alternative text ( alt=”” ). Images with null alternative text will be ignore by screen readers.

The alternative text should be consistent, clear and, most important, useful.

Alt-text is required for all images.

  • If the image is active (link, button, area) the text alternative should describe the link’s function.
  • if the image is not active but conveys information, the text alternative conveys the same information.
  • if the image is redundant or conveys no information use alt=”” for the text alternative.
  • If the image is text then the alt-text should (usually) be the same as the text in the image.

TIPS: How to write better alternative text.

  1. Write the function of the image, not its description.
  2. If the image is a link, or it’s inside a link tag, do not reference to the fact that it is a link. Screen readers will mention this anyways.
  3. Avoid words like “picture of…”, “image of…” or “link to…”
  4. Use the fewest number of words necessary.
  5. Use CSS to create graphic custom bullets. If you can not use CSS use null or “bullet” as alternative text.
  6. Include the image related to a link inside the link tag. And use null as alternative text.
  7. Use a text-only browser or hide the images on your browser to review your alternative text. You can also use an screen reader to check the page before publishing it.