+ add dropdown.less.

src/less/components/dropdowns.less

+//
+// Dropdown menus
+// --------------------------------------------------
+
+
+// Dropdown arrow/caret
+.caret
+{
+  display: inline-block;
+  width: 0;
+  height: 0;
+  margin-left: 2px;
+  vertical-align: middle;
+  border-top:   @caret-width-base solid @dropdown-caret-color;
+  border-right: @caret-width-base solid transparent;
+  border-left:  @caret-width-base solid transparent;
+  // Firefox fix for https://github.com/twbs/bootstrap/issues/9538. Once fixed,
+  // we can just straight up remove this.
+  border-bottom: 0 dotted;
+}
+
+// The dropdown wrapper (div)
+.dropdown
+{
+  position: relative;
+}
+
+// Prevent the focus on the dropdown toggle when closing dropdowns
+.dropdown-toggle:focus
+{
+  outline: 0;
+}
+
+// The dropdown menu (ul)
+.dropdown-menu
+{
+  position: absolute;
+  top: 100%;
+  left: 0;
+  z-index: @zindex-dropdown;
+  display: none; // none by default, but block on "open" of the menu
+  float: left;
+  min-width: 160px;
+  padding: 5px 0;
+  margin: 2px 0 0; // override default ul
+  list-style: none;
+  font-size: @font-size-base;
+  background-color: @dropdown-bg;
+  border: 1px solid @dropdown-fallback-border; // IE8 fallback
+  border: 1px solid @dropdown-border;
+  border-radius: @border-radius-base;
+  .box-shadow(0 6px 12px rgba(0,0,0,.175));
+  background-clip: padding-box;
+
+  // Aligns the dropdown menu to right
+  &.pull-right
+  {
+    right: 0;
+    left: auto;
+  }
+
+  // Dividers (basically an hr) within the dropdown
+  .divider
+  {
+    .nav-divider(@dropdown-divider-bg);
+  }
+
+  // Links within the dropdown menu
+  > li > a
+  {
+    display: block;
+    padding: 3px 20px;
+    clear: both;
+    font-weight: normal;
+    line-height: @line-height-base;
+    color: @dropdown-link-color;
+    white-space: nowrap; // prevent links from randomly breaking onto new lines
+  }
+}
+
+// Hover/Focus state
+.dropdown-menu > li > a
+{
+  &:hover,
+  &:focus
+  {
+    text-decoration: none;
+    color: @dropdown-link-hover-color;
+    background-color: @dropdown-link-hover-bg;
+  }
+}
+
+// Active state
+.dropdown-menu > .active > a
+{
+  &,
+  &:hover,
+  &:focus
+  {
+    color: @dropdown-link-active-color;
+    text-decoration: none;
+    outline: 0;
+    background-color: @dropdown-link-active-bg;
+  }
+}
+
+// Disabled state
+//
+// Gray out text and ensure the hover/focus state remains gray
+
+.dropdown-menu > .disabled > a
+{
+  &,
+  &:hover,
+  &:focus
+  {
+    color: @dropdown-link-disabled-color;
+  }
+}
+// Nuke hover/focus effects
+.dropdown-menu > .disabled > a
+{
+  &:hover,
+  &:focus
+  {
+    text-decoration: none;
+    background-color: transparent;
+    background-image: none; // Remove CSS gradient
+    .reset-filter();
+    cursor: not-allowed;
+  }
+}
+
+// Open state for the dropdown
+.open
+{
+  // Show the menu
+  > .dropdown-menu
+  {
+    display: block;
+  }
+
+  // Remove the outline when :focus is triggered
+  > a
+  {
+    outline: 0;
+  }
+}
+
+// Dropdown section headers
+.dropdown-header
+{
+  display: block;
+  padding: 3px 20px;
+  font-size: @font-size-small;
+  line-height: @line-height-base;
+  color: @dropdown-header-color;
+}
+
+// Backdrop to catch body clicks on mobile, etc.
+.dropdown-backdrop
+{
+  position: fixed;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  top: 0;
+  z-index: @zindex-dropdown - 10;
+}
+
+// Right aligned dropdowns
+.pull-right > .dropdown-menu
+{
+  right: 0;
+  left: auto;
+}
+
+// Allow for dropdowns to go bottom up (aka, dropup-menu)
+//
+// Just add .dropup after the standard .dropdown class and you're set, bro.
+// TODO: abstract this so that the navbar fixed styles are not placed here?
+
+.dropup,
+.navbar-fixed-bottom .dropdown
+{
+  // Reverse the caret
+  .caret
+  {
+    // Firefox fix for https://github.com/twbs/bootstrap/issues/9538. Once this
+    // gets fixed, restore `border-top: 0;`.
+    border-top: 0 dotted;
+    border-bottom: 4px solid @dropdown-caret-color;
+    content: "";
+  }
+  // Different positioning for bottom up menu
+  .dropdown-menu
+  {
+    top: auto;
+    bottom: 100%;
+    margin-bottom: 1px;
+  }
+}
+
+
+// Component alignment
+//
+// Reiterate per navbar.less and the modified component alignment there.
+
+@media (min-width: @grid-float-breakpoint)
+{
+  .navbar-right
+  {
+    .dropdown-menu
+    {
+      .pull-right > .dropdown-menu();
+    }
+  }
+}
+