Techniques for WCAG 2.0

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# G148: Not specifying background color, not specifying text color, and not using technology features that change those defaults

## Applicability

Any technology where text and background color are specified separately and browsers can control default colors.

This technique relates to:

- Success Criterion 1.4.3 (Contrast (Minimum))
  - How to Meet 1.4.3 (Contrast (Minimum))
  - Understanding Success Criterion 1.4.3 (Contrast (Minimum))
- Success Criterion 1.4.6 (Contrast (Enhanced))
  - How to Meet 1.4.6 (Contrast (Enhanced))
  - Understanding Success Criterion 1.4.6 (Contrast (Enhanced))
- Success Criterion 1.4.8 (Visual Presentation)
  - How to Meet 1.4.8 (Visual Presentation)
  - Understanding Success Criterion 1.4.8 (Visual Presentation)

## Description

The objective of this technique is to make sure that users can read text that is presented over a background. With this technique the author avoids having to do any contrast measures by simply not specifying the text color and not specifying the background. As a result the colors of both are completely determined by the user agent.

## Examples

### Example 1

Example 1: Author specifies neither text color nor background. They also do not use CSS. As a result the user can set his browser defaults to provide the colors and contrasts that work well for them.

## Resources

Resources are for information purposes only, no endorsement implied.

- Contrast Analyser – Application

- Contrast Ratio Analyser - online service

- Colour Contrast Analyser - Firefox Extension

- Color Contrast Samples

- Atypical colour response

- Colors On the Web Color Contrast Analyzer

- Tool to convert images based on color loss so that contrast is restored as luminance contrast when there was only color contrast (that was lost due to color deficiency)

- List of color contrast tools

## Related Techniques

- G18: Ensuring that a contrast ratio of at least 4.5:1 exists between text (and images of text) and background behind the text
- G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text

## Tests

### Procedure

1. Look in all places that text color can be specified

2. Check that text color is not specified

3. Look in all areas that background color or image used as a background can be specified

4. Check that no background color or image used as a background is specified

### Expected Results

- # 2 and 4 are true

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