292881 back-to-top scope: CMS wiki + content pages only

src/DfE.CheckPerformanceData.Web/Views/Page/Content.cshtml

@@ -82,7 +82,7 @@
 }
 @await Html.PartialAsync("ContentPages/_ContentNodes", content)
 
-@* Back-to-top now lives in _Layout.cshtml so every page gets it universally. *@
+@await Html.PartialAsync("ContentPages/_BackToTop")
 
 @* Equalise the height of dfe-cards that live as direct grandchildren of a govuk-grid-row.
    Flex-wrap keeps cards in the same VISUAL row equal, but cards that wrap to a new row are

src/DfE.CheckPerformanceData.Web/Views/Page/Wiki.cshtml

@@ -29,4 +29,8 @@
     </div>
 </div>
 
-@* Back-to-top now lives in _Layout.cshtml so every page gets it universally. *@
+@* Placed OUTSIDE the govuk-grid-row so its natural position is below all page content —
+   position:sticky needs the natural position to sit below the viewport for the pin to
+   engage. Rendering it here (rather than inside the one-third column) makes the wiki
+   layout behave identically to the full-width Content.cshtml pages. *@
+@await Html.PartialAsync("ContentPages/_BackToTop")

src/DfE.CheckPerformanceData.Web/Views/Shared/_AdminLayout.cshtml

@@ -192,10 +192,6 @@
         </button>
         <main class="admin-main" id="main-content">
             @RenderBody()
-            @* Universal back-to-top link — rendered inside <main> so its natural
-               position is below all page content in the admin column. Sticky until
-               the reader scrolls past the fold, then releases above the footer. *@
-            @await Html.PartialAsync("ContentPages/_BackToTop")
         </main>
     </div>
 }
@@ -213,8 +209,6 @@ else
             </button>
             <main class="admin-main" id="main-content">
                 @RenderBody()
-                @* Universal back-to-top link — see comment on the wide variant above. *@
-                @await Html.PartialAsync("ContentPages/_BackToTop")
             </main>
         </div>
     </div>
@@ -254,10 +248,5 @@ else
        responds to clicks — the shared _Layout also loads it, but admin views run under
        this layout instead. *@
     <script src="~/js/confirm-modal.js" defer></script>
-    @* Back-to-top reveal-on-scroll enhancement — loaded here for the same reason
-       as the shared _Layout: admin views don't inherit from _Layout, so the script
-       needs its own registration on the admin bundle. defer keeps the fetch off
-       the critical path. *@
-    <script src="~/js/back-to-top.js" defer asp-append-version="true"></script>
     @RenderSection("Scripts", required: false)
 }

src/DfE.CheckPerformanceData.Web/Views/Shared/_Layout.cshtml

@@ -145,12 +145,6 @@
 @Html.GovUkFrontendJsEnabledScript()
 @await Html.PartialAsync("_ContactUsBanner")
 @RenderBody()
-@* Universal back-to-top link. Rendered here (rather than per-view) so every long
-   page — search results, dashboards, admin lists, CMS content — gets it without
-   having to remember to include the partial. The script is hidden-until-scroll
-   so short pages never show it, and the container collapses to zero height while
-   hidden so no phantom footer gap. *@
-@await Html.PartialAsync("ContentPages/_BackToTop")
 @Html.GovUkFrontendScriptImports()
 
 @section Footer {

src/DfE.CheckPerformanceData.Web/Views/Shared/_ShareLayout.cshtml

@@ -29,23 +29,10 @@
 <div class="govuk-width-container">
     <main class="govuk-main-wrapper" id="main-content">
         @RenderBody()
-        @* Universal back-to-top link — long share pages (aggregate dashboards, replays)
-           benefit from a jump-to-top; the partial is hidden-until-scroll so short pages
-           see nothing. No dependency on the admin nav / GTM the rest of this layout
-           deliberately omits — just an anchor + a small enhancement script. *@
-        @await Html.PartialAsync("ContentPages/_BackToTop")
     </main>
 </div>
 @Html.GovUkFrontendScriptImports()
 
-@section BodyEnd {
-    @* Back-to-top reveal-on-scroll enhancement. Share layout otherwise runs script-
-       light (no cookies.js, no admin bundles) — this one enhancement script is
-       small and defers off the critical path so the tokened share page renders
-       fast even on constrained networks. *@
-    <script src="~/js/back-to-top.js" defer asp-append-version="true"></script>
-}
-
 @section Footer {
     <footer class="govuk-footer">
         <div class="govuk-width-container">