A "lerp" or linear interpolation is a linear equation that expresses the straight line between two [x, y] points on a plane, as a function y = f(x). This function creates a CSS calc() expression which resolves an interpolation of two static values, relative to a low/high range of a dynamic value (width, font-size, viewport dimensions) using a combination of relative and absolute units. This enables numerous applications of dynamic values in CSS including for letter-spacing, line-height, font-size, margin, padding, width and height.