twbs--bootstrap/lib/dropdowns.less

// Dropdown Menus
// Use the .menu class on any <li> element within the topbar or ul.tabs and you'll get some superfancy dropdowns
.dropdown {
  position: relative;
}
// The link that is clicked to toggle the dropdown
.dropdown-toggle:after {
  display: inline-block;
  width: 0;
  height: 0;
  margin-top: 8px;
  margin-left: 6px;
  text-indent: -99999px;
  vertical-align: top;
  border-left: 4px solid transparent;
  border-right: 4px solid transparent;
  border-top: 4px solid @white;
  .opacity(30);
  content: "\2193";
}
.dropdown:hover .dropdown-toggle:after {
  .opacity(100);
}
// The dropdown menu (ul)
.dropdown-menu {
  position: absolute;
  top: 40px;
  z-index: 900;
  float: left;
  display: none; // None by default, but block on "open" of the menu
  min-width: 160px;
  max-width: 220px;
  _width: 160px;
  padding: 6px 0;
  margin-left: 0; // override default ul styles
  margin-right: 0;
  background-color: @white;
  border-color: #999;
  border-color: rgba(0,0,0,.2);
  border-style: solid;
  border-width: 0 1px 1px;
  .border-radius(0 0 6px 6px);
  .box-shadow(0 2px 4px rgba(0,0,0,.2));
  .background-clip(padding-box);
  zoom: 1; // do we need this?

  // Unfloat any li's to make them stack
  li {
    float: none;
    display: block;
    background-color: none;
  }
  // Dividers (basically an hr) within the dropdown
  .divider {
    height: 1px;
    margin: 5px 0;
    overflow: hidden;
    background-color: #eee;
    border-bottom: 1px solid @white;
  }
}

.topbar .dropdown-menu, .dropdown-menu {
  // Links within the dropdown menu
  a {
    display: block;
    padding: 4px 15px;
    clear: both;
    font-weight: normal;
    line-height: 18px;
    color: @gray;
    text-shadow: 0 1px 0 @white;
    // Hover state
    &:hover {
      color: @grayDark;
      text-decoration: none;
      #gradient > .vertical(#eeeeee, #dddddd);
      @shadow: inset 0 1px 0 rgba(0,0,0,.025), inset 0 -1px rgba(0,0,0,.025);
      .box-shadow(@shadow);
    }
  }
}

// Open state for the dropdown
.dropdown.open {
  .dropdown-toggle {
    color: @white;
    background: #ccc;
    background: rgba(0,0,0,.3);
  }
  .dropdown-menu {
    display: block;
  }
}