@media (max-width: 640px) {
  nav input {
    width: 40px;
    height: 40px;
    z-index: 10;
    opacity: 1;
  }
  
  nav ul {
    z-index: 1;
    list-style: none;
    width: 100%;
    text-align: center;
    transform: translate(0, -100%);
    transition: all .25s linear;
    display: none;
  }
  
  nav input:checked ~ ul {
    display: block;
    transform: translate(0, 0%);
  }

  .dropdown {
    display: flex !important;
    justify-content: space-between;
  }
}

.dropdown {
  display: none;
}

.hamburger {
  align-self: flex-end;
}

label {
  cursor: pointer;
}

input[type=checkbox] + label .icon-bar {
  display: block;
  width: 22px;
  height: 2px;
  background-color: #333;
  margin: 4px;
  transition: all 0.2s;
}

input[type=checkbox] + label .top-bar {
  transform: rotate(0);
}

input[type=checkbox] + label .middle-bar {
  opacity: 1;
}

input[type=checkbox]:checked + label  .top-bar {
  transform: rotate(45deg);
  transform-origin: 10% 10%;
}

input[type=checkbox]:checked + label  .middle-bar {
  opacity: 0;
}

input[type=checkbox]:checked + label .bottom-bar {
  transform: rotate(-45deg);
  transform-origin: 10% 90%;
}