Easing CSS variables

easing.css

:root {
  --ease-in-quad: cubic-bezier(.55, .085, .68, .53);
  --ease-in-cubic: cubic-bezier(.550, .055, .675, .19);
  --ease-in-quart: cubic-bezier(.895, .03, .685, .22);
  --ease-in-quint: cubic-bezier(.755, .05, .855, .06);
  --ease-in-expo: cubic-bezier(.95, .05, .795, .035);
  --ease-in-circ: cubic-bezier(.6, .04, .98, .335);

  --ease-out-quad: cubic-bezier(.25, .46, .45, .94);
  --ease-out-cubic: cubic-bezier(.215, .61, .355, 1);
  --ease-out-quart: cubic-bezier(.165, .84, .44, 1);
  --ease-out-quint: cubic-bezier(.23, 1, .32, 1);
  --ease-out-expo: cubic-bezier(.19, 1, .22, 1);
  --ease-out-circ: cubic-bezier(.075, .82, .165, 1);

  --ease-in-out-quad: cubic-bezier(.455, .03, .515, .955);
  --ease-in-out-cubic: cubic-bezier(.645, .045, .355, 1);
  --ease-in-out-quart: cubic-bezier(.77, 0, .175, 1);
  --ease-in-out-quint: cubic-bezier(.86, 0, .07, 1);
  --ease-in-out-expo: cubic-bezier(1, 0, 0, 1);
  --ease-in-out-circ: cubic-bezier(.785, .135, .15, .86);
}

➤ Example usage

Ref.: Benjamin De Cock | Motion & Playfulness | UX Special, CSS Day 2018 @ 26:38

• "Don't rely on the built-in easing curves as the accelerations are not strong enough."
• "Most of the time an ease-out curve […] will be the best choice because the animation will kick off immediately."
• "ease-in-out can be an appropriate choice when you're moving something that is already on screen."

This is great!

May I ask what expo & circ refer to? I understand that quad through quint are exponents of an increasingly steeper polynomial which makes sense that the acceleration is ever increasing. But what about the last two?

Mind you that I have not watched the video so I apologize if it's answered in it.

"circ" is short for circular; the plot of the function looks like a quarter circle. You can visualize it with this tool: https://netcetera.org/camtf-playground.html

"expo" is a pretty steep exponential function. I'm unsure why these particular parameters have that name.