Performance concepts.
What to animate and what to avoid so the browser stays at 60fps.
opacity and visibility together.force3Dforce3D is the GSAP property that forces an animated element onto its own GPU layer by applying a 3D transform matrix even when the animation is 2D-only.overwriteoverwrite is a GSAP tween property that decides what happens when a new tween targets a property another tween is already animating.will-changewill-change is a CSS property that hints to the browser which properties are about to animate, letting it pre-promote the element to its own GPU layer.