tl;dr: Safari 27.3 beta introduces Adaptive Dark Mode, which automatically transforms light websites into dark versions for users with dark system appearance enabled, addressing the gap between the ~40% of page loads in dark mode and the ~10% of sites supporting it. WebKit analyzes page colors, inverts luminosity while preserving hue, aims for WCAG 4.5:1 contrast, and intelligently handles SVGs, bitmaps, and gradients, while leaving sites that declare `color-scheme` support untouched. To preserve privacy, Safari hides the transformation from JavaScript and canvas queries, preventing fingerprinting.