diff --git a/layouts/_partials/sidebar-tree.html b/layouts/_partials/sidebar-tree.html
index dba63f3a..e5f00807 100644
--- a/layouts/_partials/sidebar-tree.html
+++ b/layouts/_partials/sidebar-tree.html
@@ -1,37 +1,57 @@
 {{- /*
 
-  A modified version of the siderbar-tree.html partial in Docsy, adding:
-  
-  * The "toc.html" partial at L45.
+  A copy of the siderbar-tree.html partial in Docsy, modified to:
+
+  * Ignore the `sidebarRoot` parameter, because of this regression:
+    <https://github.com/google/docsy/issues/2426>
+  * Add the "toc.html" partial at L68.
 
 */ -}}
 
-{{/* We cache this partial for bigger sites and set the active class client side. */ -}}
-{{ $sidebarCacheLimit := .Site.Params.ui.sidebar_cache_limit | default 2000 -}}
-{{ $shouldDelayActive := ge (len .Site.Pages) $sidebarCacheLimit -}}
+{{ $context := .context -}}
+{{ $sidebarRoot := .sidebarRoot -}}
+{{ $sidebarRootID := .sidebarRootID -}}
+{{ $cacheSidebar := .cacheSidebar -}}
+
+{{ with $context -}}
+{{/* When the sidebar is cached, "active" class is set client side. */ -}}
+{{ $shouldDelayActive := $cacheSidebar -}}
+
 <div id="td-sidebar-menu" class="td-sidebar__inner{{ if $shouldDelayActive }} d-none{{ end }}">
   {{ if not .Site.Params.ui.sidebar_search_disable -}}
+
   <form class="td-sidebar__search d-flex align-items-center">
     {{ partial "search-input.html" . }}
-    <button class="btn btn-link td-sidebar__toggle d-md-none p-0 ms-3 fas fa-bars" type="button" data-bs-toggle="collapse" data-bs-target="#td-section-nav" aria-controls="td-section-nav" aria-expanded="false" aria-label="Toggle section navigation">
+    <button class="btn btn-link td-sidebar__toggle" type="button" {{/**/ -}}
+      data-bs-toggle="collapse" data-bs-target="#td-section-nav" {{/**/ -}}
+      aria-controls="td-section-nav" aria-expanded="false" aria-label="Toggle section navigation">
     </button>
   </form>
-  {{ else -}}
+
+  {{- else -}}
+
   <div id="content-mobile">
   <form class="td-sidebar__search d-flex align-items-center">
     {{ partial "search-input.html" . }}
-    <button class="btn btn-link td-sidebar__toggle d-md-none p-0 ms-3 fas fa-bars" type="button" data-bs-toggle="collapse" data-bs-target="#td-section-nav" aria-controls="td-section-nav" aria-expanded="false" aria-label="Toggle section navigation">
+    <button class="btn btn-link td-sidebar__toggle" type="button" {{/**/ -}}
+      data-bs-toggle="collapse" data-bs-target="#td-section-nav" {{/**/ -}}
+      aria-controls="td-section-nav" aria-expanded="false" aria-label="Toggle section navigation">
     </button>
   </form>
   </div>
   <div id="content-desktop"></div>
-  {{ end -}}
+
+  {{- end }}
+  {{/* */ -}}
+
   <nav class="td-sidebar-nav collapse
-      {{- if .Site.Params.ui.sidebar_search_disable }} td-sidebar-nav--search-disabled{{ end -}}
-      {{- if .Site.Params.ui.sidebar_menu_foldable }} foldable-nav{{ end -}}
-      " id="td-section-nav">
-    {{ if  (gt (len .Site.Home.Translations) 0) -}}
-    <div class="td-sidebar-nav__section nav-item dropdown d-block d-lg-none">
+        {{- if .Site.Params.ui.sidebar_search_disable }} td-sidebar-nav--search-disabled{{ end -}}
+        {{- if .Site.Params.ui.sidebar_menu_foldable }} foldable-nav{{ end }}" {{/**/ -}}
+      id="td-section-nav"
+      {{- if .Site.Params.ui.sidebar_root_enabled }} data-sidebar-root-id="{{ $sidebarRootID }}"{{ end -}}
+    >
+    {{ if and .Site.Params.ui.sidebar_lang_menu (gt (len .Site.Home.Translations) 0) -}}
+    <div class="td-sidebar-nav__section nav-item d-block d-lg-none">
       {{ partial "navbar-lang-selector.html" . }}
     </div>
     {{ end -}}
@@ -45,44 +65,129 @@
     {{ partial "toc.html" . }}
   </nav>
 </div>
+
+{{- end }}{{/* with $context */ -}}
+
 {{ define "section-tree-nav-section" -}}
-{{ $s := .section -}}
-{{ $p := .page -}}
-{{ $shouldDelayActive := .shouldDelayActive -}}
-{{ $sidebarMenuTruncate := .sidebarMenuTruncate -}}
-{{ $treeRoot := cond (eq .ulNr 0) true false -}}
-{{ $ulNr := .ulNr -}}
-{{ $ulShow := .ulShow -}}
-{{ $active := and (not $shouldDelayActive) (eq $s $p) -}}
-{{ $activePath := and (not $shouldDelayActive) (or (eq $p $s) ($p.IsDescendant $s)) -}}
-{{ $show := cond (or (lt $ulNr $ulShow) $activePath (and (not $shouldDelayActive) (eq $s.Parent $p.Parent)) (and (not $shouldDelayActive) (eq $s.Parent $p)) (not $p.Site.Params.ui.sidebar_menu_compact) (and (not $shouldDelayActive) ($p.IsDescendant $s.Parent))) true false -}}
-{{ $mid := printf "m-%s" ($s.RelPermalink | anchorize) -}}
-{{ $pages_tmp := where (union $s.Pages $s.Sections).ByWeight ".Params.toc_hide" "!=" true -}}
-{{ $pages := $pages_tmp | first $sidebarMenuTruncate -}}
-{{ $truncatedEntryCount := sub (len $pages_tmp) $sidebarMenuTruncate -}}
-{{ if gt $truncatedEntryCount 0 -}}
-  {{ warnf "WARNING: %d sidebar entries have been truncated. To avoid this, increase `params.ui.sidebar_menu_truncate` to at least %d (from %d) in your config file. Section: %s"
-      $truncatedEntryCount (len $pages_tmp) $sidebarMenuTruncate  $s.Path -}}
-{{ end -}}
-{{ $withChild := gt (len $pages) 0 -}}
-{{ $manualLink := cond (isset $s.Params "manuallink") $s.Params.manualLink ( cond (isset $s.Params "manuallinkrelref") (relref $s $s.Params.manualLinkRelref) $s.RelPermalink) -}}
-{{ $manualLinkTitle := cond (isset $s.Params "manuallinktitle") $s.Params.manualLinkTitle $s.Title -}}
-<li class="td-sidebar-nav__section-title td-sidebar-nav__section{{ if $withChild }} with-child{{ else }} without-child{{ end }}{{ if $activePath }} active-path{{ end }}{{ if (not (or $show $p.Site.Params.ui.sidebar_menu_foldable )) }} collapse{{ end }}" id="{{ $mid }}-li">
-  {{ if (and $p.Site.Params.ui.sidebar_menu_foldable (ge $ulNr 1)) -}}
-  <input type="checkbox" id="{{ $mid }}-check"{{ if $activePath}} checked{{ end }}/>
-  <label for="{{ $mid }}-check"><a href="{{ $manualLink }}"{{ if ne $s.LinkTitle $manualLinkTitle }} title="{{ $manualLinkTitle }}"{{ end }}{{ with $s.Params.manualLinkTarget }} target="{{ . }}"{{ if eq . "_blank" }} rel="noopener"{{ end }}{{ end }} class="align-left ps-0 {{ if $active}} active{{ end }} td-sidebar-link{{ if $s.IsPage }} td-sidebar-link__page{{ else }} td-sidebar-link__section{{ end }}{{ if $treeRoot }} tree-root{{ end }}" id="{{ $mid }}">{{ with $s.Params.Icon}}<i class="{{ . }}"></i>{{ end }}<span class="{{ if $active }}td-sidebar-nav-active-item{{ end }}">{{ $s.LinkTitle }}</span></a></label>
-  {{ else -}}
-  <a href="{{ $manualLink }}"{{ if ne $s.LinkTitle $manualLinkTitle }} title="{{ $manualLinkTitle }}"{{ end }}{{ with $s.Params.manualLinkTarget }} target="{{ . }}"{{ if eq . "_blank" }} rel="noopener"{{ end }}{{ end }} class="align-left ps-0{{ if $active}} active{{ end }} td-sidebar-link{{ if $s.IsPage }} td-sidebar-link__page{{ else }} td-sidebar-link__section{{ end }}{{ if $treeRoot }} tree-root{{ end }}" id="{{ $mid }}">{{ with $s.Params.Icon}}<i class="{{ . }}"></i>{{ end }}<span class="{{ if $active }}td-sidebar-nav-active-item{{ end }}">{{ $s.LinkTitle }}</span></a>
-  {{- end }}
-  {{- if $withChild }}
-  {{- $ulNr := add $ulNr 1 }}
-  <ul class="ul-{{ $ulNr }}{{ if (gt $ulNr 1)}} foldable{{end}}">
-    {{ range $pages -}}
-    {{ if (not (and (eq $s $p.Site.Home) (eq .Params.toc_root true))) -}}
-    {{ template "section-tree-nav-section" (dict "page" $p "section" . "shouldDelayActive" $shouldDelayActive "sidebarMenuTruncate" $sidebarMenuTruncate "ulNr" $ulNr "ulShow" $ulShow) }}
-    {{- end }}
+  {{/* cSpell:ignore manuallink manuallinkrelref manuallinktitle */ -}}
+  {{ $s := .section -}}
+  {{ $p := .page -}}
+  {{ $shouldDelayActive := .shouldDelayActive -}}
+  {{ $sidebarMenuTruncate := .sidebarMenuTruncate -}}
+  {{ $treeRoot := cond (eq .ulNr 0) true false -}}
+  {{ $ulNr := .ulNr -}}
+  {{ $ulShow := .ulShow -}}
+  {{ $active := and (not $shouldDelayActive) (eq $s $p) -}}
+  {{ $activePath := and (not $shouldDelayActive) (or (eq $p $s) ($p.IsDescendant $s)) -}}
+  {{ $show := cond
+        (or
+          (lt $ulNr $ulShow)
+          $activePath
+          (and (not $shouldDelayActive) (eq $s.Parent $p.Parent))
+          (and (not $shouldDelayActive) (eq $s.Parent $p))
+          (not $p.Site.Params.ui.sidebar_menu_compact)
+          (and (not $shouldDelayActive) ($p.IsDescendant $s.Parent))
+        )
+        true false
+  -}}
+  {{ $mid := printf "m-%s" ($s.RelPermalink | anchorize) -}}
+  {{ $pages_tmp := where (union $s.Pages $s.Sections).ByWeight ".Params.toc_hide" "!=" true -}}
+  {{ $pages := $pages_tmp | first $sidebarMenuTruncate -}}
+  {{ $truncatedEntryCount := sub (len $pages_tmp) $sidebarMenuTruncate -}}
+
+  {{ if gt $truncatedEntryCount 0 -}}
+    {{ warnf "WARNING: %d sidebar entries have been truncated. To avoid this, increase `params.ui.sidebar_menu_truncate` to at least %d (from %d) in your config file. Section: %s"
+        $truncatedEntryCount (len $pages_tmp) $sidebarMenuTruncate  $s.Path -}}
+  {{ end -}}
+
+  {{ $withChild := gt (len $pages) 0 -}}
+  {{ $manualLink :=
+      cond
+        (isset $s.Params "manuallink")
+        $s.Params.manualLink
+        (cond
+          (isset $s.Params "manuallinkrelref")
+          (relref $s $s.Params.manualLinkRelref)
+          $s.RelPermalink
+        )
+  -}}
+  {{ $manualLinkTitle :=
+      cond
+        (isset $s.Params "manuallinktitle")
+        $s.Params.manualLinkTitle
+        $s.Title
+  -}}
+  {{ if and $treeRoot (eq $s.Params.sidebar_root_for "self") -}}
+    {{ with $s.Parent -}}
+      {{ $manualLink = .RelPermalink -}}
+    {{ end -}}
+  {{ end -}}
+  <li class="td-sidebar-nav__section-title td-sidebar-nav__section
+        {{- if $withChild }} with-child{{ else }} without-child{{ end -}}
+        {{ if $activePath }} active-path{{ end -}}
+        {{ if (not (or $show $p.Site.Params.ui.sidebar_menu_foldable )) }} collapse{{ end -}}
+      " {{/**/ -}}
+      id="{{ $mid }}-li" {{- /**/ -}}
+    >
+    {{ if (and $p.Site.Params.ui.sidebar_menu_foldable (ge $ulNr 1)) -}}
+    <input type="checkbox" id="{{ $mid }}-check"{{ if $activePath}} checked{{ end }}/>
+    <label for="{{ $mid }}-check">{{/**/ -}}
+      <a href="{{ $manualLink }}"
+        {{- if ne $s.LinkTitle $manualLinkTitle }} {{/**/ -}}
+          title="{{ $manualLinkTitle }}"
+        {{- end -}}
+        {{ with $s.Params.manualLinkTarget }} {{/**/ -}}
+          target="{{ . }}"
+          {{- if eq . "_blank" }} rel="noopener"{{ end -}}
+        {{ end }} {{/**/ -}}
+        class="align-left ps-0 {{ if $active}} active{{ end }} td-sidebar-link
+          {{- if $s.IsPage }} td-sidebar-link__page
+          {{- else }} td-sidebar-link__section
+          {{- end }}
+          {{- if $treeRoot }} tree-root{{ end }}" {{/**/ -}}
+        id="{{ $mid }}" {{- /**/ -}}
+      >
+        {{- with $s.Params.Icon -}}
+          <i class="{{ . }}"></i>
+        {{- end -}}
+        <span class="{{ if $active }}td-sidebar-nav-active-item{{ end }}">
+          {{- $s.LinkTitle -}}
+        </span> {{- /**/ -}}
+      </a> {{- /**/ -}}
+    </label>
+    {{ else -}}
+      <a href="{{ $manualLink }}"
+        {{- if ne $s.LinkTitle $manualLinkTitle }} title="{{ $manualLinkTitle }}"{{ end -}}
+        {{ with $s.Params.manualLinkTarget }} {{/**/ -}}
+          target="{{ . }}"
+          {{- if eq . "_blank" }} rel="noopener"{{ end -}}
+        {{ end }} {{/**/ -}}
+        class="align-left ps-0
+          {{- if $active}} active{{ end }} {{/**/ -}}
+          td-sidebar-link
+          {{- if $s.IsPage }} td-sidebar-link__page{{ else }} td-sidebar-link__section{{ end }}
+          {{- if $treeRoot }} tree-root{{ end }}" {{/**/ -}}
+        id="{{ $mid }}" {{- /**/ -}}
+      >
+      {{- with $s.Params.Icon -}}
+        <i class="{{ . }}"></i>
+      {{- end -}}
+      <span class="
+        {{- if $active }}td-sidebar-nav-active-item{{ end -}}
+        {{- if and $s.Params.sidebar_root_for site.Params.ui.sidebar_root_enabled }} td-sidebar-root-up-icon{{ end -}}
+      ">
+        {{- $s.LinkTitle -}}
+      </span></a>
+    {{- end -}}
+    {{ if $withChild -}}
+    {{ $ulNr := add $ulNr 1 }}
+    <ul class="ul-{{ $ulNr }}{{ if (gt $ulNr 1)}} foldable{{end}}">
+      {{ range $pages -}}
+        {{ if (not (and (eq $s $p.Site.Home) (eq .Params.toc_root true))) -}}
+          {{ template "section-tree-nav-section" (dict "page" $p "section" . "shouldDelayActive" $shouldDelayActive "sidebarMenuTruncate" $sidebarMenuTruncate "ulNr" $ulNr "ulShow" $ulShow) }}
+        {{- end }}
+      {{- end }}
+    </ul>
     {{- end }}
-  </ul>
-  {{- end }}
-</li>
-{{- end -}}
+  </li>
+{{- end }}