Css tweak to dark theme, mark submenu carets (ie arrows) white, Fixes #1098

src/css/less/bootswatch.dark.less

@@ -575,3 +575,12 @@ a:hover {
 
 // MEDIA QUERIES
 // -----------------------------------------------------
+
+.caret {
+  color: @textColor
+}
+
+.dropdown-submenu > a:after {
+  border-left-color: @textColor;
+}
+