Mega dropdown - Vanilla JS - SCSS

mega-dropdown.scss

.dropdown {
  position: absolute;
  top: 30px;
  z-index: 10;
  left: 0;
  width: 300px;
  height: 300px;
  opacity: 0;
  transition: transform 0.3s, opacity 0.5s;
  will-change: transform, opacity;
  background-color: #fff;
  border-radius: 4px;
  display: flex;
  line-height: 1;
  box-shadow: 0 2px 15px 0 rgba(0, 0, 0, 0.15);

   &::before {
     content: '';
     position: absolute;
     left: 50%;
     bottom: 100%;
     border: solid transparent;
     border-color: rgba(245, 245, 240, 0);
     border-bottom-color: #fff;
     border-width: 8px;
     margin-left: -8px;
  }
}

nav {
 position: absolute;
 left: 50%;
 top: 0;
 transform: translateX(-50%);
}