Simple animated mobile hamburger menu

hamburger-menu.scss

#hamburger {
  color: white;
  font-size: 2rem;
  width: inherit;
  z-index: 501;

  .line {
    width: 30px;
    height: 4px;
    background-color: #ecf0f1;
    display: block;
    margin: 5px auto;
    transition: all 0.3s ease-in-out;
  }

  &.opened {
    .line:nth-child(2) {
      opacity: 0;
    }

    .line:nth-child(1) {
      transform: translateY(13px) rotate(45deg);
    }

    .line:nth-child(3) {
      transform: translateY(-5px) rotate(-45deg);
    }
  }

  &:hover {
    cursor: pointer;
  }
}

// HTML markup
//
// <div id="hamburger">
//   <span class="line"></span>
//   <span class="line"></span>
//   <span class="line"></span>
// </div>