var colorsBig = document.querySelector('.big-color');
var colorsElements = document.querySelectorAll('ul li');

for(var colorElement of colorsElements) {
	colorElement.onmouseenter = function(event) {
		colorsBig.classList.remove('hidden');
		var targetX = event.target;
		var location = targetX.getBoundingClientRect().x;
    colorsBig.style.left = location + 'px'
	}
	colorElement.onmouseleave = function() {
		colorsBig.classList.add('hidden');
	}
}