guideline: Distinguishable
Create content that’s easy to see and hear.
1.4.1 Use of Color
Color must not be the only way to convey information. Always provide an additional visual cue, like icon, text label, underline, shape, or pattern (e.g. striped, solid).
1.4.2 Audio Control
If audio plays automatically for more than 3 seconds, it must be possible to pause the audio, stop the audio, or adjust the volume, without using system-wide controls.
1.4.3 Contrast (Minimum)
Text contrast against its background must be at least 4.5:1 for normal text, or 3:1 for large text (over 24px, or bold and over 19px).
1.4.4 Resize Text
Text remains readable and usable when zoomed to 200%.
1.4.5 Images of Text
Text must be actual text, not images of text, unless a specific visual presentation is absolutely necessary (e.g. logo).
1.4.6 Contrast (Enhanced)
Text contrast against its background must be at least 7:1 for normal text, or 4.5:1 for large text (over 24px, or bold and over 19px).
1.4.7 Low or No Background Audio
For prerecorded audio with speech, any background sound must be at least 20dB lower than the speech, or there must be a way to turn it off.
1.4.8 Visual Presentation
Blocks of text (like paragraphs) must have a line height of at least 1.5, not be justified, and stay within 80 characters (or 40 for CJK scripts). Allow users to adjust spacing and colors using custom styles.
1.4.9 Images of Text (No Exception)
Text must be actual text, not images of text (no exception, not even for design or aesthetic reasons).
1.4.10 Reflow
Content remains functional and easy to read when; zoomed to 400% or; viewed at 320px width, without needing to scroll in two directions (except for tables, maps, and similar content).