1.4.10 - Reflow

Summary

On smaller devices or when content is zoomed there should be no loss of information or functionality, and users should not be required to scroll content both vertically and horizontally.

Requirements

• Make sure that all content and functionality are available on 320pt-wide screens.
• Make sure your pages are responsive and the content will ‘reflow’ to a single column gracefully.
• A simple browser based test is to view the page with a viewport width of 320px, or 1280px at 400% zoom.
  • You can zoom in on a Mac in Chrome by pressing Command and + key, until you see the resolution hit 400%.

Common mistakes

• Content does not reflow to a single column when zoomed.
• Horizontal scrolling appears in both directions at some low resolutions when content is zoomed.
• Using fixed sized containers and fixed position content.

Why?

• People who are sight impaired often use screen magnification to resize page content and this can cause info to get lost.
• Scrolling can often be difficult for some disabled users, more so when horizontally or both horizontally and vertically at the same time.

Official wording in the Web Content Accessibility Guidelines

1.4.10 Reflow (Level AA): Content can be presented without loss of information or functionality, and without requiring scrolling in two dimensions for:

• Vertical scrolling content at a width equivalent to 320 CSS pixels;
• Horizontal scrolling content at a height equivalent to 256 CSS pixels.

Except for parts of the content which require two-dimensional layout for usage or meaning.

Note: 320 CSS pixels is equivalent to a starting viewport width of 1280 CSS pixels wide at 400% zoom. For web content which is designed to scroll horizontally (e.g., with vertical text), 256 CSS pixels is equivalent to a starting viewport height of 1024 CSS pixels at 400% zoom.

Examples of content which requires two-dimensional layout are images, maps, diagrams, video, games, presentations, data tables, and interfaces where it is necessary to keep toolbars in view while manipulating content.

See the W3C's detailed explanation of this guideline with techniques and examples.

Guidance for Design

Guidance for Web

See the W3C's detailed explanation of this guideline with techniques and examples.

Displaying code

The use of <code><pre> formatted content (such as code) can cause horizontal scrolling. Using the CSS declarations such as word-wrap: break-word; on <code><pre> in small viewports will help to avoid horizontal scrolling at all.