Added "link outside" and "link inside" classes to reference nodes.

Distinguishes hyperlinks that are outside of current sphinx hierarchy.

sphinx/environment.py

@@ -168,13 +168,26 @@ class CitationReferences(Transform):
             refnode += nodes.Text('[' + cittext + ']')
             citnode.parent.replace(citnode, refnode)
 
+class CategorizeReferences(Transform):
+    """Categorize references (hyperlinks) as link outside or link inside"""
+
+    default_priority = 619
+    def apply(self):
+        for reference in self.document.traverse(nodes.reference):
+            if reference.hasattr('refuri'):
+                refuri = reference['refuri']
+                if re.match(r"(?:http|https|ftp)://", refuri):
+                    classes = ("link", "outside")
+                else:
+                    classes = ("link", "inside")
+                reference["classes"].extend(classes)
 
 class SphinxStandaloneReader(standalone.Reader):
     """
     Add our own transforms.
     """
     transforms = [CitationReferences, DefaultSubstitutions, MoveModuleTargets,
-                  HandleCodeBlocks, SortIds]
+                  HandleCodeBlocks, SortIds, CategorizeReferences]
 
     def get_transforms(self):
         return standalone.Reader.get_transforms(self) + self.transforms

sphinx/themes/default/static/default.css_t

@@ -147,7 +147,8 @@ div.sphinxsidebar input {
     font-size: 1em;
 }
 
-/* -- body styles ----------------------------------------------------------- */
+
+/* -- hyperlink styles ------------------------------------------------------ */
 
 a {
     color: {{ theme_linkcolor }};
@@ -163,6 +164,48 @@ a:hover {
     text-decoration: underline;
 }
 
+div.toctree-wrapper a,
+div.toctree-wrapper a:visited,
+div#indices-and-tables a,
+div#indices-and-tables a:visited,
+div.sphinxsidebar a,
+div.sphinxsidebar a:visited,
+div.related a,
+div.related a:visited {
+    text-decoration: none;
+}
+
+div.toctree-wrapper a:hover,
+div#indices-and-tables a:hover,
+div.sphinxsidebar a:hover,
+div.related a:hover {
+ text-decoration: underline;
+ }
+
+a.link.outside {
+   text-decoration: none;
+   border-bottom: 1px dashed {{ theme_linkcolor }};
+} 
+
+a.link.outside:hover {
+   text-decoration: none;
+   border-bottom: none;
+} 
+
+/* To distinguish between internal & external references uncomment following */
+/*
+a.reference,
+a.reference em {
+    font-style: normal;
+}
+
+a.reference.internal em {
+    font-style: italic;
+}
+*/
+
+/* -- body styles ----------------------------------------------------------- */
+
 div.body h1,
 div.body h2,
 div.body h3,