Sub-Heading-styling for chapters

display/display.css

@@ -293,6 +293,8 @@
     display: flex;
     flex-direction: column;
     position: relative;
+    font-weight: bold;
+    opacity: 85%;
 }
 
 .activation-hover, .collapsible:hover {

display/overlays/neighbors.js

@@ -41,6 +41,7 @@ class NodeNeighborOverlay {
         coll.style.fontWeight = "bold";
         coll.style.textAlign = "center";
         coll.style.fontSize = "20px";
+        coll.style.opacity = "100%";
 
         // Div that displays the information about all the chapters
         var contentTabs = Helpers.createDiv(