A list of accessibility recommendations, tips and resources.
Typography
- Nest headings in order (for example, h1, h2, h3)
- Don’t skip heading levels
- Use semantic mark-up (for example, headings, lists and blockquotes)
- Links should look like links (for example, blue and underlined)
- Don’t rely on link title attribute
- Lines should be less than 80 characters wide
- Add suitable vertical spacing between lines and paragraphs
- Avoid italics, block capitals or justified text
- Use a san-serif font with thick letters
- Make sure text can be resized
Written content
- Use plain English
- Explain unusual words and jargon
- Put the most important information at the start
- Explain what a user has to do in a clear and concise way
- Use headings and lists to break the content into chunks
- Download links labels should include file format and size
- Headings, links and button text must be unique and descriptive
- Each page should have a unique, descriptive h1 and page title
Tables
- Make sure tables are accessible
- Only use tables to present data
- Use tables as accessible alternatives to charts and infographics
- Split complex tables into multiple small ones
- Use correct table markup for headers, rows and cells, so screen reader users can understand and navigate them
Charts
Read this blog post about making charts more accessible
Colour and contrast
- Check colour contrast between text and background
- Check design works in black and white
- Don’t communicate using colour alone
- Check design works in high contrast mode
Interaction
- Check design is functional when using a keyboard to navigate
- Check it’s visually apparent which page element has current keyboard focus
- Complex interface components, like sliders, should be avoided when simple solutions, like a text input, can be used instead
- If an experience cannot be made accessible, create another route for users to get that information
Forms
- All form inputs should have labels and be linked with a ‘for’ attribute
- Forms and interactive elements should have useful hints
- Error messages should suggest ways to fix errors
- Error messages should show a summary of errors above the h1 and move focus to it
- Error message summaries should include an h1 message that tells the screen reader user there is a problem, and give a list of descriptive errors with links to the relevant fields
Images
- Images should have good alternative text
- If images are purely decorative, then they need an empty alt tag
alt="" - Avoid using images of text
Layout and structure
- Layout should be consistent and predictable
- Do not rely upon shape, size, or visual location (for example, “Click the square icon to continue” or “Instructions are in the right-hand column”)
- Check reading and navigation order is logical
- Check page is readable and functional when text size is doubled
- Don’t use duplicate id attributes
iframes
- Use the iframe title attribute to give the content a descriptive title
- Make sure interactive elements inside an iframe are usable with a keyboard
- Make sure interactive elements have a clear focus style
- Test the iframe is readable and functional with browser zoom at 200%
- Test the content doesn’t overflow or become truncated when font size is increased
Manual tests
- Use the service with a keyboard only – no mouse
- Check the page with CSS off
- Increase font size to 200%
- Test in high contrast mode
- Check html mark-up is valid
- Check in a range of browsers and devices
- Check using assistive technologies
