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Web Accessibility Academy · Lesson

Why Contrast Ratios Exist

How the eye and the math behind 4.5 to 1 connect.

What Contrast Really Means

When you read text, your eye is comparing how light or dark the letters are against the background. That gap is contrast. 👀

Why We Need a Number

One designer says a color looks fine, another squints. To settle it, accessibility uses a contrast ratio, a single measurable number anyone can check.

All lessons in this course

  1. Why Contrast Ratios Exist
  2. Hitting AA: Text and Large Text Thresholds
  3. Never Rely on Color Alone
  4. Checking Contrast With Free Tools
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