refs #18316 [finc] sets visited links color

* introduces scss variable for visited links, use steel (gray) as default
* intoduces a:visited definition using that variable

co-authored by: Alexander Purr <purr@ub.uni-leipzig.de>
* add description

themes/finc/scss/_customVariables.scss

@@ -59,6 +59,8 @@ $modal-close-color-hover: $brand-danger !default;
 
 //// Anchor/Link text decoration
 $textdecoration-anchor: none !default;
+// needs to be overriden in catalogues if visited color does not fit - AP
+$a-visited-color: $steel !default;
 
 //// FORM FEEDBACK states colors and, by default, alerts colors (i.e. alerts are
 //// defined like so '$alert-success-bg: $state-success-bg;')

themes/finc/scss/compiled.scss

@@ -566,6 +566,11 @@ select {
 // LINKS // ANCHORS
 a {
   text-decoration: $textdecoration-anchor;
+
+  // set different color for links already visited
+  &:visited {
+    color: $a-visited-color;
+  }
 }
 
 // LINKS - END