Basic MetisMenu style.

metis.css

.sidebar-nav a,
.sidebar-nav a:active,
.sidebar-nav a:focus,
.sidebar-nav a:hover{
  outline: none;
}
.sidebar-nav ul a,
.sidebar-nav ul li{
  display: block;
}
.sidebar-nav ul a:hover{
  background: rgba(255, 255, 255, 0.2);
  text-decoration: none;
}
.sidebar-nav ul a{
  background: #45283C;
  border-top: 1px solid rgba(0, 0, 0, 0.3);
  box-shadow: 0px 1px 0px rgba(255, 255, 255, 0.05) inset;
  color: #AAA;
  padding: 10px 20px;
  text-shadow: 0px 1px 0px rgba(0, 0, 0, 0.5);
}
.sidebar-nav ul ul a:hover{
  background: rgba(255, 255, 255, 0.2);
  text-decoration: none;
}
.sidebar-nav ul ul a{
  background: #663931;
  padding: 10px 30px;
}
.sidebar-nav ul ul ul a:hover{
  background: rgba(255, 255, 255, 0.2);
  text-decoration: none;
}
.sidebar-nav ul ul ul a{
  background: #8F563B;
  padding: 10px 40px;
}
.sidebar-nav ul{
  list-style: none;
  margin: 0;
  padding: 0;
}
.sidebar-nav{
  background-image: -webkit-linear-gradient(left, color-stop(#333333 10px), color-stop(#222222 10px));
  background-image: linear-gradient(to right, #333333 10px, #222222 10px);
  background-repeat: repeat-x;
  border-bottom: 1px solid rgba(0, 0, 0, 0.3);
  filter: progid: DXImageTransform.Microsoft.gradient(startColorstr='#ff333333', endColorstr='#ff222222', GradientType=1);
}
.sidebar-nav-item{
  padding-left: 5px;
}
.sidebar-nav-icon{
  padding-right: 5px;
}
.sidebar{
  background: #333;
  display: block;
  float: left;
  width: 100%;
}