🐛 Fix styles hiding highlightparent plugin

plugin filename had typo, when z-index: -1 was removed from dokuwiki__content::before side-effects
on highlightparent weren't checked

css/area_content.less

@@ -27,16 +27,6 @@
                 clear: both;
                 padding-top: 1em; // as h1
             }
-
-            #plugin__highlightparent {
-                clear: none;
-                display: block;
-
-                + * {
-                    clear: both;
-                    padding-top: 1em; // as h1
-                }
-            }
         }
     }
 }

css/plugins/highlight_parent.less

@@ -5,6 +5,17 @@
 
 /* + + + + +  global  + + + + + */
 
+#plugin__highlightparent {
+    clear: none;
+    display: block;
+    position: relative;
+
+    + * {
+        clear: both;
+        padding-top: 1em; // as h1
+    }
+}
+
 @media @screen_max-md {
     #plugin__highlightparent {
         clear: both;