fix menu layout

assets/_custom.scss

@@ -1,3 +1,20 @@
 /* You can add custom styles here. */
 
 // @import "plugins/numbered";
+.book-menu-content nav {
+    display: flex;
+    flex-direction: column;
+    height: 99%;
+}
+
+.book-brand {
+    margin: 0;
+}
+.book-search {
+    margin: 0;
+}
+
+.book-menu-mid {
+    margin-top: -1rem;
+    flex-grow: 1;
+}

layouts/partials/docs/brand.html

@@ -5,4 +5,5 @@
     {{- end -}}
     <span>{{ .Site.Title }}</span>
   </a>
+  <hr>
 </h2>

layouts/partials/docs/menu.html

@@ -1,21 +1,24 @@
 <nav>
-{{ partial "docs/brand" . }}
-{{ partial "docs/search" . }}
+  {{ partial "docs/brand" . }}
+  {{ partial "docs/search" . }}
 
+  <div class="book-menu-top">
+  {{ partial "docs/inject/menu-before" . }}
+  {{ partial "docs/menu-hugo" .Site.Menus.before }}
+  </div>
 
-{{ partial "docs/inject/menu-before" . }}
-{{ partial "docs/menu-hugo" .Site.Menus.before }}
+  <div class="book-menu-mid">
+  {{ if .Site.Params.BookMenuBundle }}
+    {{ partial "docs/menu-bundle" . }}
+  {{ else }}
+    {{ partial "docs/menu-filetree" . }}
+  {{ end }}
+  </div>
 
-{{ if .Site.Params.BookMenuBundle }}
-  {{ partial "docs/menu-bundle" . }}
-{{ else }}
-  {{ partial "docs/menu-filetree" . }}
-{{ end }}
-
-<div style="bottom:0; position:fixed;">
-{{ partial "docs/menu-hugo" .Site.Menus.after }}
-{{ partial "docs/inject/menu-after" . }}
-</div>
+  <div class="book-menu-bot">
+    {{ partial "docs/inject/menu-after" . }}
+    {{ partial "docs/menu-hugo" .Site.Menus.after }}
+  </div>
 </nav>
 
 <!-- Restore menu position as soon as possible to avoid flickering -->