Add link styling

Author: mmxw

docs/static/css/theme.css

@@ -1,15 +1,21 @@
 [data-md-color-scheme="kraken"] {
   color-scheme: light;
-
   --md-primary-fg-color: #180048;
-
   --md-accent-fg-color: #F050F8;
   --doc-symbol-module-fg-color: #F050F8;
 }
 
 [data-md-color-scheme="slate"] {
   --md-primary-fg-color: #180048;
-
   --md-accent-fg-color: #F050F8;
   --doc-symbol-module-fg-color: #F050F8;
 }
+
+/* External link icon */
+.md-content a[href^="http"]:after {
+  content: "↗";
+  font-size: 0.7em;
+  opacity: 0.7;
+  margin-left: 0.1em;
+  vertical-align: super;
+}