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Unlike web pages, PDF documents are not responsive and do not adjust to your screen size, such as on a mobile device. This forces the user to have to zoom in and the swipe left to right /right to left in order to read the content.
8. Allow Keyboard Control for Touchscreen Devicesrelated guidelines for touchscreen devices
Allow mobile devices to be operated by external physical keyboards or alternative on-screen keyboards.
Ensure that content accessed through a mobile device does not "trap" keyboard focus within subsections of content.
Ensure that when mobile keyboard users or mobile screen reader users navigate sequentially through content on a mobile device, they encounter information in an order that is consistent with the meaning of the content.
Help mobile keyboard users and mobile screen reader users know which element has the keyboard focus.
WCAG Mobile Related Guidelines
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