[ruslan_mart]

.gruppi-toggle.hidden {
   display: none;
}

(function(){
	function handler(event, method, current, target) {
		current['on' + event] = current.classList[method].bind(target || current, 'hidden');
	};
	
	var btn = document.querySelectorAll('.gruppi-toggle'),
		block = document.querySelectorAll('.speciali-gruppi-window'),
		screenIsMin = window.screen.width < 960,
		i, method = screenIsMin ? 'toggle' : 'remove';
	
	for(i = 0; i < btn.length; i++) {
		handler('click', method, btn[i], block[i]);
		if(!screenIsMin) {
			handler('mouseleave', 'add', block[i]);
		}
	}
})();