CSS Animations Between Media Queries

CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during :hover, and we also create keyframe-based animations by adding a className, but did you know you can animate elements using media queries as the trigger? Let's have a look!

The CSS

The syntax for creating these animations and transitions is the same between media queries as it is between element states; the only difference is actually enacting them between the media queries:

/* base state */
#layout { 
	position: relative; 
	width: 900px; 
	border: 1px solid #ccc; 
	height: 200px; 
	
	/* animate width over a given duration */
	transition: width 2s;
}
.child {
	top: 0; 
	bottom: 0;
	width: 290px;
	position: absolute;
	opacity: 1;
	font-size: 20px;
	overflow: hidden;
	transform: translate3d(0, 0, 0);
	
	/* animate opacity, left, width over a given duration */
	transition: opacity 2s, width 2s, left 2s, font-size 2s, color 2s;
}
	#child1 { left: 0; background: lightblue; }
	#child2 { left: 300px; background: lightgreen; }
	#child3 { left: 600px; background: lightyellow; }

/* 
	When the client has 860 width or less:
	 	- animate the first two elements to be wider
		- fade out and hide the third element
		- animate the background colors
		- animate the font-size of the block
*/
@media screen and (max-width: 860px) {
	#layout { width: 600px; }
	.child { width: 290px; font-size: 12px; }
	#child1 { left: 0; background: blue; color: #fff; }
	#child2 { left: 300px; background: green; color: #fff; }
	#child3.child { /* hider */ opacity: 0; width: 0; }
}

The creativity is all in the developer's hands; animating media queries isn't difficult, but the use of them is more interesting. Some sites used to animate the position of structure elements during window resize, which is nice but how often is that a realistic usage? A more realistic usage is with mobile devices, animating elements when orientation changes:

/* base mobile styles */
#sidebar {
	transition: opacity 2s;
	width: 300px;
	overflow: hidden;
}

/* portrait */
@media screen and (orientation:portrait) { 
	/* portrait-specific styles */ 
	#sidebar {
		opacity: 0;
		width: 0;
	}
}

/* landscape */
@media screen and (orientation:landscape) {
	/* landscape-specific styles */
	#sidebar {
		opacity: 1;
	}
}

The animation above triggers when the device goes from portrait to landscape, and visa versa. This is incredibly useful when hiding a pane in portrait view and elegantly showing that pane when the user switches to landscape view.

CSS animations between media queries have traditionally been a delicacy of web design, but there are practical uses. The best part of them? There is no JavaScript involved and you can force CSS hardware acceleration if you'd like. Take a few moments to look at your mobile site to see if you can add this effect.