simple menu trigger icon

cd-nav-trigger

.cd-nav-trigger {
  /* navigation trigger - visible on mobile devices only */
  float: right;
  position: relative;
  display: block;
  width: 34px;
  height: 44px;
  margin-right: 5%;
  /* hide text */
  overflow: hidden;
  white-space: nowrap;
  color: transparent;
}
.cd-nav-trigger span, .cd-nav-trigger span::before, .cd-nav-trigger span::after {
  /* hamburger icon in CSS */
  position: absolute;
  display: inline-block;
  height: 3px;
  width: 24px;
  background: #ffffff;
}
.cd-nav-trigger span {
  /* line in the center */
  position: absolute;
  top: 50%;
  right: 5px;
  margin-top: -2px;
  -webkit-transition: background 0.2s;
  -moz-transition: background 0.2s;
  transition: background 0.2s;
}
.cd-nav-trigger span::before, .cd-nav-trigger span::after {
  /* other 2 lines */
  content: '';
  right: 0;
  /* Force Hardware Acceleration in WebKit */
  -webkit-transform: translateZ(0);
  -moz-transform: translateZ(0);
  -ms-transform: translateZ(0);
  -o-transform: translateZ(0);
  transform: translateZ(0);
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  -webkit-transform-origin: 0% 50%;
  -moz-transform-origin: 0% 50%;
  -ms-transform-origin: 0% 50%;
  -o-transform-origin: 0% 50%;
  transform-origin: 0% 50%;
  -webkit-transition: -webkit-transform 0.2s;
  -moz-transition: -moz-transform 0.2s;
  transition: transform 0.2s;
}
.cd-nav-trigger span::before {
  /* menu icon top line */
  top: -6px;
}
.cd-nav-trigger span::after {
  /* menu icon bottom line */
  top: 6px;
}
.cd-nav-trigger.nav-is-visible span {
  /* hide line in the center */
  background: rgba(255, 255, 255, 0);
}
.cd-nav-trigger.nav-is-visible span::before, .cd-nav-trigger.nav-is-visible span::after {
  /* keep visible other 2 lines */
  background: white;
}
.cd-nav-trigger.nav-is-visible span::before {
  -webkit-transform: translateX(4px) translateY(-3px) rotate(45deg);
  -moz-transform: translateX(4px) translateY(-3px) rotate(45deg);
  -ms-transform: translateX(4px) translateY(-3px) rotate(45deg);
  -o-transform: translateX(4px) translateY(-3px) rotate(45deg);
  transform: translateX(4px) translateY(-3px) rotate(45deg);
}
.cd-nav-trigger.nav-is-visible span::after {
  -webkit-transform: translateX(4px) translateY(2px) rotate(-45deg);
  -moz-transform: translateX(4px) translateY(2px) rotate(-45deg);
  -ms-transform: translateX(4px) translateY(2px) rotate(-45deg);
  -o-transform: translateX(4px) translateY(2px) rotate(-45deg);
  transform: translateX(4px) translateY(2px) rotate(-45deg);
}