Allow "Contents" summary to scroll in a fixed div

In the unfortunate event that the "Contents" summary doesn't fit
vertically (like in the "Prelude"), it will be scrollable.

haddock-api/resources/html/NewOcean.std-theme/new-ocean.css

@@ -81,6 +81,9 @@ body.js-enabled .hide-when-js-enabled {
     position: fixed;
     max-width: 10vw;
     top: 10.2em;
+    left: 2em;
+    bottom: 1em;
+    overflow-y: scroll;
   }
 
   #synopsis {
@@ -96,10 +99,6 @@ body.js-enabled .hide-when-js-enabled {
     z-index: 1;
   }
 
-  #table-of-contents {
-    left: 2em;
-  }
-
   #synopsis .show {
     border: 1px solid #5E5184;
     padding: 0.7em;
@@ -518,7 +517,7 @@ div#style-menu-holder {
 /* @group Front Matter */
 
 #synopsis .caption,
-#table-of-contents .caption {
+#contents-list .caption {
   font-size: 1rem;
 }
 
@@ -526,26 +525,25 @@ div#style-menu-holder {
   font-size: 16px;
 }
 
-#table-of-contents {
+#contents-list {
   background:  #f7f7f7;
   padding: 1em;
   margin: 0;
-  margin-top: 1em;
 }
 
-#table-of-contents .caption {
+#contents-list .caption {
   text-align: left;
   margin: 0;
 }
 
-#table-of-contents ul {
+#contents-list ul {
   list-style: none;
   margin: 0;
   margin-top: 10px;
   font-size: 14px;
 }
 
-#table-of-contents ul ul {
+#contents-list ul ul {
   margin-left: 1.5em;
 }
 

haddock-api/src/Haddock/Backends/Xhtml.hs

@@ -633,9 +633,9 @@ ppModuleContents pkg qual exports orphan
   | null sections && not orphan  = noHtml
   | otherwise                    = contentsDiv
  where
-  contentsDiv = divTableOfContents << (
+  contentsDiv = divTableOfContents << (divContentsList << (
     sectionName << "Contents" +++
-    unordList (sections ++ orphanSection))
+    unordList (sections ++ orphanSection)))
 
   (sections, _leftovers{-should be []-}) = process 0 exports
   orphanSection

haddock-api/src/Haddock/Backends/Xhtml/Layout.hs

@@ -15,7 +15,7 @@ module Haddock.Backends.Xhtml.Layout (
 
   divPackageHeader, divContent, divModuleHeader, divFooter,
   divTableOfContents, divDescription, divSynopsis, divInterface,
-  divIndex, divAlphabet, divModuleList,
+  divIndex, divAlphabet, divModuleList, divContentsList,
 
   sectionName,
   nonEmptySectionName,
@@ -80,7 +80,7 @@ nonEmptySectionName c
 
 divPackageHeader, divContent, divModuleHeader, divFooter,
   divTableOfContents, divDescription, divSynopsis, divInterface,
-  divIndex, divAlphabet, divModuleList
+  divIndex, divAlphabet, divModuleList, divContentsList
     :: Html -> Html
 
 divPackageHeader    = sectionDiv "package-header"
@@ -88,6 +88,7 @@ divContent          = sectionDiv "content"
 divModuleHeader     = sectionDiv "module-header"
 divFooter           = sectionDiv "footer"
 divTableOfContents  = sectionDiv "table-of-contents"
+divContentsList     = sectionDiv "contents-list"
 divDescription      = sectionDiv "description"
 divSynopsis         = sectionDiv "synopsis"
 divInterface        = sectionDiv "interface"