Function blend_across 

pub fn blend_across(value: f64, from: f64, to: f64) -> f64

A blend between two values as a layout’s size crosses a range, eased so it is flat at both ends: 0 at or below from, 1 at or above to, and a smoothstep between. A responsive change driven by width or height (a stage cross-fading between breakpoints) moves at the same shape a motion does, rather than snapping at the breakpoint.