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Considerations for developers


  • Navigating through the <h1> and <h2> give a user an overview of a page and how its content is structured. The <h3> through <h6> elements provide a quick understanding of the details in each section.
  • Heading tags should be in order. That means an <h1> is followed by an <h2>, an <h2> is followed by a <h2> or <h3> and so on. It is ok to skip heading levels when going up in order (ex. <h4> to <h1>).
  • Keep heading tags consistent. Inconsistently implementing headings can create confusion and frustration for users using assistive technologies.
  • Don’t style text to give the visual appearance of headings – use actual heading tags.

Source – A11y style guide


  • Creating accessible lists is fairly straight-forward and easy if you use the correct mark-up.
  • Use ol markup to group ordered lists; use ul markup to group unordered lists; and use dl markup to group terms with their definitions.
  • Simple comma-separated lists may not need list markup, but longer lists or groups of links should have it.

Source – A11y style guide

Considerations for designers

Make sure that the user can easily read the text on the page.

  • Headings should be chosen to represent the actual hierarchical structure of the page.

  • Use a font size sufficient for comfortable reading. The minimal font size for the body text is 16 pixels, but this size may vary depending on the font style.

  • Set the paragraph width for comfortable reading. Don't make paragraphs too long or too short: 45 to 75 characters is an acceptable length, 66 is optimal. Shorter text is good for forms, image captions, and unimportant notes.

  • Choose a legible font. It's recommended to use sans serif fonts for interfaces and serif fonts for long documents, but this isn’t an absolute rule. Make sure that your font:

    • Reads well regardless of the scale
    • Has large-height lowercase letters (x-height)
    • Is sufficiently large in the selected size
    • Has constant parameters for letter forms (lowercase letter height and other parameters)
    • Has unique characters that cannot be confused with each other, for example 0 and O
    • Supports all necessary symbols and styles
  • Use headings to draw the user's attention to the page hierarchy. Make sure that the headings differ from the main text in size, thickness, style, and color. This will ensure visual consistency and readability with the main text.

  • Determine the height of the text for optimal reading. The larger the font size and line thickness, the larger the spacing should be. For the body text, the spacing to font size ratio should be around 1.4–1.65, for headings – 1–1.3, for captions and short lines – around 1.3. Lines that are spaced too tightly or too loosely make text less readable, so finding a new line becomes more difficult.


Use of Color – color isn’t used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A)

Text Spacing – in content implemented using markup languages, no loss of content or functionality occurs. (Level AA)

Contrast (Minimum) – the visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for some cases. (Level AA)

Resize Text – except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality. (Level AA)

Images of Text – if the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text. (Level AA)

Visual Presentation(Level AAA)

Other recommendations

See more accessibility recommendations in the common Accessibility guide.

Released under the MIT License.

Released under the MIT License.