.three-d {
  perspective: 200px;
  transition: all .07s linear;
  position: relative;
  cursor: pointer;
}
  /* complete the animation! */
  .three-d:hover .three-d-box, 
  .three-d:focus .three-d-box {
    transform: translateZ(-25px) rotateX(90deg);
  }

.three-d-box {
  transition: all .3s ease-out;
  transform: translatez(-25px);
  transform-style: preserve-3d;
  pointer-events: none;
  position: absolute;
  top: 0;
  left: 0;
  display: block;
  width: 100%;
  height: 100%;
}

/* 
  put the "front" and "back" elements into place with CSS transforms, 
  specifically translation and translatez
*/
.front {
  transform: rotatex(0deg) translatez(25px);
}

.back {
  transform: rotatex(-90deg) translatez(25px);
  color: #ffe7c4;
}

.front, .back {
  display: block;
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  background: black;
  padding: 15px 10px;
  color: white;
  pointer-events: none;
  box-sizing: border-box;
}

.back {
  background: #222;
}


nav {
  display: block;
  background: #000;
  width: 92%;
  border-radius: 40px;
  box-shadow: 0 8px 6px -6px black;
}

.menu { display: block; }

.menu li {
  display: inline-block;
  position: relative;
  z-index: 100;
}

.menu li:first-child { margin-left: 0; }

.menu li a {
  font-weight: 600;
  text-decoration: none;
  padding: 14px 18px;
  display: block;
  color: #000;
  text-align: center;
  transition: all 0.2s ease-in-out 0s;
}

.menu li a:hover,
.menu li:hover>a {
  color: #fff;
  background: #00b0f0;
  border-radius: 34px;
}

.menu ul {
  visibility: hidden;
  opacity: 0;
  margin: 0;
  padding: 0;
  width: 170px;
  position: absolute;
  left: 0px;
  background: #fff;
  z-index: 99;
  transform: translate(0, 20px);
  transition: all 0.2s ease-out;
}

.menu ul:after {
  bottom: 100%;
  left: 20%;
  border: solid transparent;
  content: " ";
  height: 0;
  width: 0;
  position: absolute;
  pointer-events: none;
  border-color: rgba(255, 255, 255, 0);
  border-bottom-color: #fff;
  border-width: 6px;
  margin-left: -6px;
}

.menu ul li {
  display: block;
  float: none;
  background: none;
  margin: 0;
  padding: 0;
}

.menu ul li a {
  font-size: 12px;
  font-weight: normal;
  display: block;
  color: #797979;
  background: #fff;
}

.menu ul li a:hover,
.menu ul li:hover>a {
  background: #000;
  color: #fff;
}

.menu li:hover>ul {
  visibility: visible;
  opacity: 1;
  transform: translate(0, 0);
}

.menu ul ul {
  left: 169px;
  top: 0px;
  visibility: hidden;
  opacity: 0;
  transform: translate(20px, 20px);
  transition: all 0.2s ease-out;
}

.menu ul ul:after {
  left: -6px;
  top: 10%;
  border: solid transparent;
  content: " ";
  height: 0;
  width: 0;
  position: absolute;
  pointer-events: none;
  border-color: rgba(255, 255, 255, 0);
  border-right-color: #fff;
  border-width: 6px;
  margin-top: -6px;
}

.menu li>ul ul:hover {
  visibility: visible;
  opacity: 1;
  transform: translate(0, 0);
}

.responsive-menu {
  display: none;
  width: 100%;
  padding: 20px 15px;
  background: #00aff0;
  color: #fff;
  text-transform: uppercase;
  font-weight: 600;
}

.responsive-menu:hover {
  background: #00aff0;
  color: #fff;
  text-decoration: none;
}

a.homer { background: #00b0f0;border-radius: 34px; }
 @media (min-width: 768px) and (max-width: 979px) {

.mainWrap { width: 768px; }

.menu ul { top: 37px; }

.menu li a { font-size: 12px; }

a.homer { background: #00aff0; }
}
 @media (max-width: 767px) {

.mainWrap {
  width: auto;
  padding: 50px 20px;
}

.menu { display: none; }

.responsive-menu { display: block; }

nav {
  margin: 0;
  background: none;
}

.menu li {
  display: block;
  margin: 0;
}

.menu li a {
  background: #fff;
  color: #797979;
}

.menu li a:hover,
.menu li:hover>a {
  background: #00aff0;
  color: #fff;
}

.menu ul {
  visibility: hidden;
  opacity: 0;
  top: 0;
  left: 0;
  width: 100%;
  transform: initial;
}

.menu li:hover>ul {
  visibility: visible;
  opacity: 1;
  position: relative;
  transform: initial;
}

.menu ul ul {
  left: 0;
  transform: initial;
}

.menu li>ul ul:hover { transform: initial; }
}