gistfile1.js

;( function( $ ) {
	var 	$background,
		mouse = {
			x: 0, // Current x-axis position of mouse
			y: 0 // Current y-axis position of mouse
		};

	$( document ).on( 'mousemove', function( event ) {
		mouse.x = event.clientX || event.pageX;
		mouse.y = event.clientY || event.pageY;

		if ( $background && $background.length )
			$background.css( {
				'transform': 'translate( ' + ( ( $( window ).width() / 2 - mouse.x ) / $( window ).width() * 100 ) + 'px, ' + ( ( $( window ).height() / 2 - mouse.y ) / $( window ).height() * 100 ) + 'px )'
			} );
	} );

	$( document ).on( 'ready', function() {
		$background = $( '.background-wrapper' );
	} );
} ) ( jQuery )