dropdown fixes and dropdown docs tweaks

dist/css/bootstrap.css

@@ -3007,7 +3007,7 @@ input[type="button"].btn-block {
   border-radius: .25rem;
 }
 
-.dropdown-menu .divider {
+.dropdown-menu .dropdown-divider {
   height: 1px;
   margin: .5rem 0;
   overflow: hidden;

docs/components/dropdowns.md

@@ -13,10 +13,10 @@ Dropdowns are toggleable, contextual overlays for displaying lists of links and
 
 ## Example
 
-Wrap the dropdown's trigger and the dropdown menu within `.dropdown`, or another element that declares `position: relative;`. Then add the menu's HTML.
+Wrap the dropdown's trigger and the dropdown menu within `.dropdown`, or another element that declares `position: relative;`. Then, add the menu's HTML.
 
 {% example html %}
-<div class="dropdown">
+<div class="dropdown open">
   <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
     Dropdown
   </button>
@@ -38,10 +38,8 @@ Wrap the dropdown's trigger and the dropdown menu within `.dropdown`, or another
 
 By default, a dropdown menu is automatically positioned 100% from the top and along the left side of its parent. Add `.dropdown-menu-right` to a `.dropdown-menu` to right align the dropdown menu.
 
-{% callout warning %}
+{% callout info %}
-#### May require additional positioning
+**Heads up!** Dropdowns are positioned only with CSS and may need some additional styles for exact alignment.
-
-Dropdowns are automatically positioned via CSS within the normal flow of the document. This means dropdowns may be cropped by parents with certain `overflow` properties or appear out of bounds of the viewport. Address these issues on your own as they arise.
 {% endcallout %}
 
 {% highlight html %}

docs/dist/css/bootstrap.css

@@ -3007,7 +3007,7 @@ input[type="button"].btn-block {
   border-radius: .25rem;
 }
 
-.dropdown-menu .divider {
+.dropdown-menu .dropdown-divider {
   height: 1px;
   margin: .5rem 0;
   overflow: hidden;

scss/_dropdown.scss

@@ -50,7 +50,7 @@
   @include box-shadow(0 6px 12px rgba(0,0,0,.175));
 
   // Dividers (basically an hr) within the dropdown
-  .divider {
+  .dropdown-divider {
     @include nav-divider($dropdown-divider-bg);
   }