Laws of UX
Von Restorff Effect
The item that differs from the rest is most remembered (isolation effect). Highlight CTAs, error states, and new features by making them visually distinct. But don't rely on color alone (WCAG 1.4.1).
In plain terms
The one thing that looks different gets remembered — handy for highlighting a key button (but don't rely on color alone).
Why this matters
Making the key action stand out helps everyone find it fast — but lean on more than color, or color-blind and low-vision users miss the very thing you highlighted.