Styles define the visual presentation of content. Information must remain readable and understandable even when CSS is unavailable or disabled.

Objectives

• Improve content comprehension for users who access ebooks non-visually or use reading systems that do not support embedded stylesheets.

Implementation

• Apply rigorous structural (e.g., h1, h2, p) and semantic (e.g., em, strong) HTML markup to ensure content order and meaning are preserved without stylesheets.

Control

• Use ACE to verify the logical structure of the content (refer to the “Outlines” tab in the ACE report).
• Verify that content remains readable; for example, ensure transparent images are still visible if their legibility depends on a CSS background-color property.