Go back to single colon pseudo elements.

This is for backwards compatibility with the browsers we support in v3.

docs/assets/less/algolia.less

@@ -23,7 +23,7 @@
     }
 
     // Caret
-    &::before {
+    &:before {
       display: none !important;
     }
 
@@ -72,7 +72,7 @@
     padding: 0 !important;
 
     // Vertical divider between column header and content
-    &::before {
+    &:before {
       display: none !important;
     }
   }

docs/assets/less/examples.less

@@ -33,7 +33,7 @@
   box-shadow: inset 0 3px 6px rgba(0, 0, 0, .05);
 }
 // Echo out a label for the example
-.bs-example::after {
+.bs-example:after {
   position: absolute;
   top: 15px;
   left: 15px;
@@ -199,7 +199,7 @@
 .bs-navbar-top-example {
   padding-bottom: 45px;
 }
-.bs-navbar-top-example::after {
+.bs-navbar-top-example:after {
   top: auto;
   bottom: 15px;
 }

docs/assets/less/misc.less

@@ -80,7 +80,7 @@ h1[id] {
 
 /* Nullify ill-advised printing of hrefs; see #18711 */
 @media print {
-  a[href]::after {
+  a[href]:after {
     content: "" !important;
   }
 }

docs/examples/blog/blog.css

@@ -61,7 +61,7 @@ h6, .h6 {
 .blog-nav .active {
   color: #fff;
 }
-.blog-nav .active::after {
+.blog-nav .active:after {
   position: absolute;
   bottom: 0;
   left: 50%;