inside each .item when mouse hovers over element .trigger add .open class to .triggered element inside each .item when mouse moves over element .trigger remove .open class to .triggered element (by askjarvis.io)

javascript.js

var acionadores = document.querySelectorAll('.item .acionador');

for (var i = 0; i < acionadores.length; i++) {
    acionadores[i].addEventListener('mouseover', function() {
        this.parentNode.querySelector('.acionado').classList.add('aberto');
    });
    acionadores[i].addEventListener('mouseout', function() {
        this.parentNode.querySelector('.acionado').classList.remove('aberto');
    });
}