<ul class="menu cf">
  <li><a href="#">Home</a></li>
  <li>
    <a href="#">Lessons</a>
    <ul class="submenu">
      <li><a href="#">CSS3</a></li>
      <li><a href="#">HTML5</a></li>
      <li><a href="#">PHP</a></li>
      <li><a href="#">JavaScript</a></li>
    </ul>
  </li>
  <li><a href="#">Contacts</a></li>
  <li><a href="#">About Us</a></li>
</ul>
html {
  height: 100%;
}
body {
  background: 
    -webkit-linear-gradient(rgba(5, 610, 255, 0.4), rgba(135, 60, 255, 0.0) 80%),
    -webkit-linear-gradient(-45deg, rgba(120, 155, 255, 0.9) 25%, rgba(255, 160, 65, 0.9) 76%);
}
.cf:before, .cf:after {
  content:" ";
  display: table;
}
.cf:after {
  clear: both;
}
.cf {
  *zoom: 1;
}
.menu {
  list-style:none;
  margin: 50px auto;
  width: 800px;
  width: -moz-fit-content;
  width: -webkit-fit-content;
  width: fit-content;
}
.menu > li {
  background: #34495e;
  float: left;
  position: relative;
  -webkit-transform: skewX(25deg);
}
.menu a {
  display: block;
  color: #fff;
  text-transform: uppercase;
  text-decoration: none;
  font-family: Arial, Helvetica;
  font-size: 14px;
}
.menu li:hover {
  background: #e74c3c;
}
.menu > li > a {
  -webkit-transform: skewX(-25deg);
  padding: 1em 2em;
}
/* Dropdown */
.submenu {
  position: absolute;
  width: 200px;
  left: 50%;
  margin-left: -100px;
  -webkit-transform: skewX(-25deg);
  -webkit-transform-origin: left top;
}
.submenu li {
  background-color: #34495e;
  position: relative;
  overflow: hidden;
}
.submenu > li > a {
  padding: 1em 2em;
}
.submenu > li::after {
  content:'';
  position: absolute;
  top: -125%;
  height: 100%;
  width: 100%;
  box-shadow: 0 0 50px rgba(0, 0, 0, .9);
}
/* Odd stuff */
.submenu > li:nth-child(odd) {
  -webkit-transform: skewX(-25deg) translateX(0);
}
.submenu > li:nth-child(odd) > a {
  -webkit-transform: skewX(25deg);
}
.submenu > li:nth-child(odd)::after {
  right: -50%;
  -webkit-transform: skewX(-25deg) rotate(3deg);
}
/* Even stuff */
.submenu > li:nth-child(even) {
  -webkit-transform: skewX(25deg) translateX(0);
}
.submenu > li:nth-child(even) > a {
  -webkit-transform: skewX(-25deg);
}
.submenu > li:nth-child(even)::after {
  left: -50%;
  -webkit-transform: skewX(25deg) rotate(3deg);
}
/* Show dropdown */
.submenu, .submenu li {
  opacity: 0;
  visibility: hidden;
}
.submenu li {
  transition: .2s ease -webkit-transform;
}
.menu > li:hover .submenu, .menu > li:hover .submenu li {
  opacity: 1;
  visibility: visible;
}
.menu > li:hover .submenu li:nth-child(even) {
  -webkit-transform: skewX(25deg) translateX(15px);
}
.menu > li:hover .submenu li:nth-child(odd) {
  -webkit-transform: skewX(-25deg) translateX(-15px);
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.