GUIDE深度 · Deep dive
Choosing Text Contrast
Text-background contrast drives readability. WCAG AA requires at least 4.5:1 for body text and 3:1 for large text; color alone should not convey status, so add text or icons.
Thresholds
Body text 4.5:1; large text (18pt+ or 14pt bold) 3:1.
AA is the minimum; AAA is higher (7:1/4.5:1).
Practical tips
Light text on dark backgrounds and dark text on light backgrounds; avoid mid-gray on mid-color.
Check with a contrast tool instead of judging by eye.
FAQ
Is 4.5:1 a legal requirement?
It depends on jurisdiction and sector; WCAG is a widely used baseline.
Do icons need contrast too?
Yes; non-text content often needs 3:1.