1.4.10 Reflow (Level AA)
Help people with low vision by allowing the browser zoom function to increase the size of most content to 400%.

About

This requirement is basically related to responsive web design which is absolute must-have in these days.

Authors should allow the browser zoom function to increase the size of most content up to 400% without requiring scrolling in more than one direction.

Example:

BBC website and Bahrain.bh