Sidebar: Add a `hidden` value for `toc_status`.

src/document/sidebar.ml

···
   url : Url.t;
   valid_link : bool;
   content : Inline.t;
-  toc_status : [ `Open ] option;
+  toc_status : [ `Open | `Hidden ] option;
 }
 
 open Odoc_index
···
                 let name = Odoc_model.Paths.Identifier.name entry.id in
                 [ inline (Text name) ]
           in
-          { url; content; toc_status; valid_link = true }
+          let valid_link =
+            match entry.kind with
+            | Page { toc_status = Some `Hidden; _ } -> false
+            | _ -> true
+          in
+          { url; content; toc_status; valid_link }
     in
     let f x =
       match x.Entry.kind with

src/document/sidebar.mli

···
   url : Url.t;
   valid_link : bool;
   content : Inline.t;
-  toc_status : [ `Open ] option;
+  toc_status : [ `Open | `Hidden ] option;
 }
 
 type t = entry Tree.forest

src/driver/landing_pages.ml

···
 
 let library ~dirs ~pkg ~index lib =
   let content ppf =
-    Format.fprintf ppf "%@toc_status open\n";
+    Format.fprintf ppf "%@toc_status hidden\n";
     Format.fprintf ppf "{0 Library [%s]}@\n" lib.Packages.lib_name;
     let print_module m =
       if not m.Packages.m_hidden then

src/html_support_files/odoc.css

···
     margin-bottom: 10px;
 }
 
-.odoc-toc.odoc-global-toc > ul > li > ul > li > a {
+.odoc-toc.odoc-global-toc > ul > li > ul > li {
     font-weight: 500;
     font-size: 500;
+}
+
+.odoc-toc.odoc-global-toc > ul > li > ul > li > a {
+    font-weight: inherit;
+    font-size: inherit;
 }
 
 .odoc-toc.odoc-global-toc > ul > li > a {

src/model/frontmatter.ml

···
 type line =
   | Children_order of child Location_.with_location list
   | Short_title of short_title
-  | Toc_status of [ `Open ]
+  | Toc_status of [ `Open | `Hidden ]
 
 type children_order = child Location_.with_location list Location_.with_location
 
 type t = {
   children_order : children_order option;
   short_title : short_title option;
-  toc_status : [ `Open ] option;
+  toc_status : [ `Open | `Hidden ] option;
 }
 
 let empty = { children_order = None; short_title = None; toc_status = None }
···
    { Location_.value = `Paragraph [ { Location_.value = `Word "open"; _ } ]; _ };
   ] ->
       Result.Ok (Location_.at loc (Toc_status `Open))
-  | _ -> Error (Error.make "@toc_status can only take the 'open' value" loc)
+  | [
+   {
+     Location_.value = `Paragraph [ { Location_.value = `Word "hidden"; _ } ];
+     _;
+   };
+  ] ->
+      Result.Ok (Location_.at loc (Toc_status `Hidden))
+  | _ ->
+      Error
+        (Error.make "@toc_status can only take the 'open' and 'hidden' value"
+           loc)
 
 let of_lines lines =
   Error.catch_warnings @@ fun () -> List.fold_left apply empty lines

src/model/frontmatter.mli

···
 type t = {
   children_order : children_order option;
   short_title : short_title option;
-  toc_status : [ `Open ] option;
+  toc_status : [ `Open | `Hidden ] option;
 }
 
 val empty : t

src/model_desc/lang_desc.ml

···
             (t.short_title
               :> Comment.inline_element Location_.with_location list option)),
           Option Comment_desc.inline_element );
+      F
+        ( "toc_status",
+          (fun t ->
+            Option.map
+              (function `Hidden -> "hidden" | `Open -> "open")
+              t.toc_status),
+          Option string );
     ]
 
 and child =