Ensure visitors can view content using various methods and sizes. When setting up responsive breakpoints, account for visitors using a very small screen (think iPhone 4). Allow for the ability to zoom in (and enlarge the text) up to 200% without having to scroll in two directions.
Provide a plain text alternative for text-embedded images (e.g., on graphics and charts). Be sure that site editors have an easy way to manage text alternatives. The ‘figure’ element is a good choice.
Indicate the language of the page using the “lang” global attribute. Include this attribute on elements of pages where language changes.