html,
body {
margin: 0;
padding: 0;
}body {
width: 380px;
min-height: 280px;
padding: 10px;
font-family: “Arial”, sans-serif;
font-size: 14px;
line-height: 1.4;
background: #ecf0f1;
}.main-menu, .sub-menu {
padding: 0;
margin: 0;
width: 200px;
display: block;
}.main-menu li {
list-style: none;
background: #2980b9;
border-bottom: 2px solid #2c3e50;
}.main-menu a {
color: white;
text-decoration: none;
display: block;
padding: 10px 15px;
}.main-menu .opened{
background: #1abc9c;
position: relative;
}.main-menu .sub-menu {
position: absolute;
left: 180px;
top: 0px;
}.main-menu .sub-menu li {
background: #1abc9c;
border-bottom: 2px solid #2ecc71;
}