Accessible color is simpler than most people think. The core principle is straightforward: text needs to be easy to read, and interactive elements need to be easy to see. The technical standards (WCAG) translate this into measurable numbers, but the intuition behind them is something anyone can grasp.
The Squint Test
Squint at your screen until everything blurs. Can you still tell where the text is? Can you identify the buttons? If elements disappear when you squint, they lack sufficient contrast. This informal test is surprisingly accurate because squinting reduces your visual acuity to something closer to what a low-vision user experiences normally.
Light on Light Fails. Dark on Dark Fails.
The most common accessibility failure is simple: light gray text on a white background, or medium blue on dark blue. When the foreground and background are in the same lightness range, contrast is insufficient regardless of how different the hues are. Accessible color is primarily about lightness difference.
The Easy Fix
Every palette needs anchors at both ends of the lightness spectrum: a very light color for backgrounds and a very dark color for text. These extremes pair well with virtually any other color. PaletteRx calls these Light Base and Dark Base, and they are the single most important colors in your palette for accessibility.
When Hue Matters
Hue matters for meaning, not just contrast. Red for errors, green for success, blue for information. But these color meanings must always be reinforced with text, icons, or other non-color indicators because some users cannot distinguish hues reliably.