content/_sass/accordion.scss

.accordion-menu ul li i:before, .accordion-menu ul li i:after {
  transition: all 0.25s ease-in-out;
}

.accordion-menu ul ul li {
  animation: flipdown 0.5s ease both;
}

.accordion-menu label {
  color: rgba(0,0,0,0.8);
  cursor: pointer;
  display: block;
  font-size: 1em;
  padding: .20em 15px;
  text-transform: uppercase;
}

.accordion-menu ul {
  list-style: none;
  perspective: 900;
  padding: 0;
  margin: 0;
}
.accordion-menu ul li {
  position: relative;
  padding: 0;
  margin: 0;
  padding-bottom: 4px;
  padding-top: 18px;
}

.accordion-menu ul li:last-of-type {
  padding-bottom: 0;
}

.accordion-menu ul li.has-children {
  margin-right: 1em;
}

.accordion-menu ul li i {
  position: absolute;
  transform: translate(-6px, 0);
  margin-top: 16px;
  right: 0;
}
.accordion-menu ul li i:before, .accordion-menu ul li i:after {
  content: "";
  position: absolute;
  background-color: #ff6873;
  width: 3px;
  height: 9px;
}
.accordion-menu ul li i:before {
  transform: translate(-2px, 0) rotate(45deg);
}
.accordion-menu ul li i:after {
  transform: translate(2px, 0) rotate(-45deg);
}
.accordion-menu ul li input[type=checkbox] {
  position: absolute;
  cursor: pointer;
  width: 100%;
  height: 100%;
  opacity: 0;
}
.accordion-menu ul li input[type=checkbox]:checked ~ ul  {
  margin-top: 0;
  max-height: 0;
  opacity: 0;
  transform: translate(0, 50%);
}
.accordion-menu ul li input[type=checkbox]:checked ~ i:before {
  transform: translate(2px, 0) rotate(45deg);
}
.accordion-menu ul li input[type=checkbox]:checked ~ i:after {
  transform: translate(-2px, 0) rotate(-45deg);
}