Accessible Palette: stop using HSL for color systems

Recently, the author embarked on a project to reconstruct a color system in Postmark. The project aimed to address issues with the old palette, such as inconsistent perceived lightness of colors and unpredictable contrast ratios. The author discovered that the HSL color model, which was commonly used, was not suitable for building a color system because it did not reflect human perception. Instead, the author recommended using the CIELAB or LCh color space, which is designed to cover the entire range of visible colors and closely matches human perception of lightness. The author then introduced the Accessible Palette app, which allows users to build color systems with consistent lightness and predictable contrast ratios. The app is flexible and can accommodate existing brand colors.

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