Add a glyph to external links to visually mark them as external

src/css/globals.css

@@ -79,4 +79,16 @@ aside {
   height: fit-content;
   max-width: 50ch;
   padding: var(--space-size-xs);
+}
+
+a[target="_blank"]::after {
+  content: " \f08e";
+  font-family: "font awesome 6 free";
+  font-style: normal;
+  font-variant: normal;
+  text-rendering: auto;
+  font-weight: 900;
+  -webkit-font-smoothing: antialiased;
+  font-size: var(--text-size-xs);
+  vertical-align: super;
 }