.nav > li {
  position: relative;}
.nav a {
  display: block;
  padding: 10px;
  text-decoration: none;
  color: #333;}
.sub-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  width:100%;
  background-color: #fff;
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);}
.sub-menu a{line-height:40px !important;}
.nav li:hover > .sub-menu {
  display: block;}