_dropdown.scss

// The dropdown wrapper (div)
.dropup,
.dropdown {
  position: relative;
}

.dropdown-toggle {
  // Generate the caret automatically
  &::after {
    display: inline-block;
    width: 0;
    height: 0;
    margin-left: .25rem;
    vertical-align: middle;
    content: "";
    border-top: $caret-width solid;
    border-right: $caret-width solid transparent;
    border-left: $caret-width solid transparent;
  }

  // Prevent the focus on the dropdown toggle when closing dropdowns
  &:focus {
    outline: 0;
  }
}

.dropup {
  .dropdown-toggle {
    &::after {
      border-top: 0;
      border-bottom: $caret-width solid;
    }
  }
}

// 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
  font-size: $font-size-base;
  text-align: left; // Ensures proper alignment if parent has it changed (e.g., modal footer)
  list-style: none;
  background-color: $dropdown-bg;
  background-clip: padding-box;
  border: 1px solid $dropdown-border;
  @include border-radius($border-radius);
  @include box-shadow(0 6px 12px rgba(0,0,0,.175));
}

// Dividers (basically an hr) within the dropdown
.dropdown-divider {
  @include nav-divider($dropdown-divider-bg);
}

// Links, buttons, and more within the dropdown menu
//
// `<button>`-specific styles are denoted with `// for <button>s`
.dropdown-item {
  display: block;
  width: 100%; // For `<button>`s
  padding: 3px 20px;
  clear: both;
  font-weight: normal;