Font Smoothing Weight Delta

Calculate perceived font weight shift.

On macOS, applying -webkit-font-smoothing: antialiased to light text on a dark background physically drops the perceived weight of the font by roughly 100-200 units on a standard 100-900 axis.

If you design a UI using Inter Regular (400) in Figma (which doesn't accurately simulate browser smoothing), it will render closer to Light (300) in WebKit/Blink browsers when antialiased against a dark background.

Correction Table
Intended WeightCSS Fallback Weight
400 (Regular)500 (Medium)
500 (Medium)600 (SemiBold)
700 (Bold)800 (ExtraBold)