Easing variables

Variables that can be reused for transition-timing-function properties, more powerful than the built-in ease, ease-in, ease-out and ease-in-out.

<div class="easing-variables">Hover</div>

:root {
	/* Place variables in here to use globally */
}

.easing-variables {
	--ease-in-quad: cubic-bezier(0.55, 0.085, 0.68, 0.53);
	--ease-in-cubic: cubic-bezier(0.55, 0.055, 0.675, 0.19);
	--ease-in-quart: cubic-bezier(0.895, 0.03, 0.685, 0.22);
	--ease-in-quint: cubic-bezier(0.755, 0.05, 0.855, 0.06);
	--ease-in-expo: cubic-bezier(0.95, 0.05, 0.795, 0.035);
	--ease-in-circ: cubic-bezier(0.6, 0.04, 0.98, 0.335);

	--ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
	--ease-out-cubic: cubic-bezier(0.215, 0.61, 0.355, 1);
	--ease-out-quart: cubic-bezier(0.165, 0.84, 0.44, 1);
	--ease-out-quint: cubic-bezier(0.23, 1, 0.32, 1);
	--ease-out-expo: cubic-bezier(0.19, 1, 0.22, 1);
	--ease-out-circ: cubic-bezier(0.075, 0.82, 0.165, 1);

	--ease-in-out-quad: cubic-bezier(0.455, 0.03, 0.515, 0.955);
	--ease-in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1);
	--ease-in-out-quart: cubic-bezier(0.77, 0, 0.175, 1);
	--ease-in-out-quint: cubic-bezier(0.86, 0, 0.07, 1);
	--ease-in-out-expo: cubic-bezier(1, 0, 0, 1);
	--ease-in-out-circ: cubic-bezier(0.785, 0.135, 0.15, 0.86);
	display: inline-block;
	width: 75px;
	height: 75px;
	padding: 10px;
	color: white;
	line-height: 50px;
	text-align: center;
	background: #333;
	transition: transform 1s var(--ease-out-quart);
}

.easing-variables:hover {
	transform: rotate(45deg);
}

Demo

See the pen on CodePen.

Explanation

The variables are defined globally within the :root CSS pseudo-class which matches the root element of a tree representing the document. In HTML, :root represents the <html> element and is identical to the selector html, except that its specificity is higher.