No loss of content or functionality should occur if the user adjusts a line, word, or letter spacing.
Make sure you have a minimum 3:1 color contrast ratio for user interface components and states and graphical objects that convey meaningful information.
No loss of content or functionality should occur on mobile devices at 320 pixels width. No horizontal scrolling should be necessary unless content cannot be resized effectively.
Content should display in the orientation that works best for the user.
Provide ample opportunity for users to review and correct any potential errors, especially those that may have a big impact.