Tips: Avoiding Common Color Accessibility Pitfalls with @weable/a11y-color-utils

Ensuring your website or application is accessible involves many factors, and color contrast is a critical one. Many users, including those with visual impairments or color vision deficiencies, rely on sufficient contrast to perceive content clearly. Failing to provide adequate contrast is one of the most common accessibility mistakes.

This article highlights common pitfalls related to color accessibility and explains how the @weable/a11y-color-utils library can help you avoid them.

Pitfall 1: Insufficient Text-to-Background Contrast

• The Problem: Text that is too light on a light background, or too dark on a dark background, becomes difficult or impossible for many users to read. This is the most frequent color accessibility issue found online.
• WCAG Guideline: Success Criterion 1.4.3 Contrast (Minimum) requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text (or graphical objects/UI components).
• How @weable/a11y-color-utils Helps:
  • checkContrast(color1, color2): Directly calculates the WCAG 2.1 contrast ratio between two colors and tells you if it passes AA or AAA levels for normal and large text.
  • calculateAPCA(textColor, backgroundColor): Calculates contrast using the more modern and perceptually accurate APCA standard (expected for WCAG 3). This provides a score (Lc value) that relates more closely to human perception, especially in dark mode or with mid-range colors where WCAG 2.1 can be misleading.
  • Usage: Regularly check key text/background combinations (e.g., body text on background, button text on button background, link text on background) using these functions during design and development.

import { checkContrast, calculateAPCA } from '@weable-tools/a11y-color-utils';

const textColor = '#757575'; // Gray text
const bgColor = '#FFFFFF'; // White background

const wcagInfo = checkContrast(textColor, bgColor);
console.log(`WCAG Ratio: ${wcagInfo.ratio.toFixed(2)}:1, Passes AA: ${wcagInfo.pass}`); // Output: WCAG Ratio: 4.50:1, Passes AA: true

const apcaScore = calculateAPCA(textColor, bgColor);
console.log(`APCA Score: Lc ${apcaScore.toFixed(1)}`); // Output: APCA Score: Lc 60.1 (Good for large/bold, borderline/low for body text)

Pitfall 2: Relying Solely on Color to Convey Information

• The Problem: Using color alone (e.g., red for errors, green for success) to indicate state or meaning excludes users with color vision deficiencies (like red-green color blindness) who cannot distinguish the colors.
• WCAG Guideline: Success Criterion 1.4.1 Use of Color states that color should not be the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.
• How @weable/a11y-color-utils Helps (Indirectly): While the library focuses on contrast, ensuring good luminance contrast (lightness/darkness difference) often helps mitigate issues for colorblind users, as they primarily perceive brightness differences. Use checkContrast or calculateAPCA to ensure your chosen colors (e.g., error red vs. background) have sufficient lightness difference, in addition to using other cues like icons, text labels, or patterns.

Pitfall 3: Poor Contrast in Non-Text Elements (UI Components, Graphics)

• The Problem: Important UI elements like button borders, input field boundaries, focus indicators, icons, and meaningful parts of graphics/charts need sufficient contrast against their adjacent background to be perceivable.
• WCAG Guideline: Success Criterion 1.4.11 Non-text Contrast requires a contrast ratio of at least 3:1 for these elements.
• How @weable/a11y-color-utils Helps: Use checkContrast(color1, color2) to verify the 3:1 ratio for these non-text elements. Remember to check the element against its immediate background.

Pitfall 4: Inconsistent or Unpredictable Link Colors

• The Problem: Users expect links to be visually distinct from surrounding text. If link colors lack sufficient contrast with the background or with the surrounding text (and aren't distinguished by other means like underlining), users may not identify them as interactive elements.
• WCAG Guideline: While not a specific contrast rule, G183: Using a contrast ratio of 3:1 with surrounding text and providing additional visual cues on focus for links or controls is a common technique.
• How @weable/a11y-color-utils Helps: Use checkContrast to ensure your link color meets the 4.5:1 ratio against the background and at least a 3:1 ratio against the surrounding non-link text color.

Pitfall 5: Problems with Dark Mode Contrast

• The Problem: As discussed in the APCA research, the WCAG 2.1 contrast algorithm doesn't accurately predict perceived contrast in dark mode (light text on dark backgrounds). It often overestimates contrast, leading to designs that pass WCAG 2.1 but are still difficult to read.
• How @weable/a11y-color-utils Helps: calculateAPCA was specifically designed to handle both light and dark modes accurately. Relying on APCA scores (aiming for minimum Lc values based on font size/weight, e.g., Lc 75 for body text) will give you a much better indication of readability in dark themes.

Pitfall 6: Ignoring Contrast Needs for Different Font Weights/Sizes

• The Problem: Thinner fonts or smaller text sizes are inherently harder to read and require more contrast than larger, bolder text to achieve the same level of readability.
• WCAG Guideline: WCAG 2.1 differentiates between normal (4.5:1) and large text (3:1), but doesn't account for font weight nuances.
• How @weable/a11y-color-utils Helps: APCA explicitly considers font weight and size. While our library's calculateAPCA function itself doesn't take font size as input, you should use its Lc score output in conjunction with the APCA Readability Criterion guidelines, which specify different minimum Lc scores for various font size/weight combinations (e.g., Lc 90 for thin/small fonts, Lc 75 for standard body text, Lc 60 for larger/bolder text).

Conclusion

Color accessibility is crucial for creating inclusive interfaces. By being aware of these common pitfalls and utilizing tools like @weable/a11y-color-utils to check both WCAG 2.1 and APCA contrast values, you can make informed design decisions and build products that are usable by a wider range of people. Remember to test regularly and consider the context (font size, weight, element type) when evaluating contrast.