diff --git a/.drone.yml b/.drone.yml
index 8800024..d309d94 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -15,7 +15,7 @@ steps:
   - gulp default
 
 - name: test
-  image: klakegg/hugo:0.59.1-ext-alpine
+  image: klakegg/hugo:0.69.0-ext-alpine
   commands:
   - cd exampleSite/
   - mkdir themes/ && ln -s ../../. themes/hugo-geekdoc && hugo-official
@@ -72,7 +72,7 @@ steps:
   - curl -L https://github.com/xoxys/hugo-geekdoc/releases/latest/download/hugo-geekdoc.tar.gz | tar -xz -C exampleSite/themes/hugo-geekdoc/ --strip-components=1
 
 - name: test
-  image: klakegg/hugo:0.59.1-ext-alpine
+  image: klakegg/hugo:0.69.0-ext-alpine
   commands:
   - cd exampleSite/ && hugo-official
 
diff --git a/README.md b/README.md
index d03593b..35f7465 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # Hugo Geekdoc Theme
 
 [![Build Status](https://img.shields.io/drone/build/xoxys/hugo-geekdoc?logo=drone)](https://cloud.drone.io/xoxys/hugo-geekdoc)
-[![Hugo Version](https://img.shields.io/badge/hugo-0.55-blue.svg)](https://gohugo.io)
+[![Hugo Version](https://img.shields.io/badge/hugo-0.65-blue.svg)](https://gohugo.io)
 [![GitHub release](https://img.shields.io/github/v/release/xoxys/hugo-geekdoc)](https://github.com/xoxys/hugo-geekdoc/releases/latest)
 [![License: MIT](https://img.shields.io/github/license/xoxys/hugo-geekdoc)](LICENSE)
 
diff --git a/exampleSite/config.yaml b/exampleSite/config.yaml
index 09dced4..7278905 100644
--- a/exampleSite/config.yaml
+++ b/exampleSite/config.yaml
@@ -16,6 +16,7 @@ markup:
       unsafe: true
   tableOfContents:
     startLevel: 1
+    endLevel: 9
 
 params:
   geekdocToC: 3
diff --git a/exampleSite/content/_index.md b/exampleSite/content/_index.md
index e341f91..6c7862b 100644
--- a/exampleSite/content/_index.md
+++ b/exampleSite/content/_index.md
@@ -3,7 +3,7 @@ title: Documentation
 ---
 
 [![Build Status](https://img.shields.io/drone/build/xoxys/hugo-geekdoc?logo=drone)](https://cloud.drone.io/xoxys/hugo-geekdoc)
-[![Hugo Version](https://img.shields.io/badge/hugo-0.55-blue.svg)](https://gohugo.io)
+[![Hugo Version](https://img.shields.io/badge/hugo-0.65-blue.svg)](https://gohugo.io)
 [![GitHub release](https://img.shields.io/github/v/release/xoxys/hugo-geekdoc)](https://github.com/xoxys/hugo-geekdoc/releases/latest)
 [![License: MIT](https://img.shields.io/github/license/xoxys/hugo-geekdoc)](LICENSE)
 
@@ -16,7 +16,3 @@ Geekdoc is a simple Hugo theme for documentations. This work is inspired and par
 - Customisable
 - Zero initial configuration
 - Handy shortcodes
-
-## Requirements
-
-- Hugo 0.55 or higher
diff --git a/layouts/shortcodes/button.html b/layouts/shortcodes/button.html
index ea04661..aa05c10 100644
--- a/layouts/shortcodes/button.html
+++ b/layouts/shortcodes/button.html
@@ -2,16 +2,16 @@
 {{ $target := "" }}
 
 {{ with .Get "href" }}
-    {{ $ref = . }}
-    {{ $target = "_blank" }}
+  {{ $ref = . }}
+  {{ $target = "_blank" }}
 {{ end }}
 
 {{ with .Get "relref" }}
-    {{ $ref = relref $ . }}
+  {{ $ref = relref $ . }}
 {{ end }}
 
 <span class="gdoc-button{{ with .Get "class" }} {{ . }}{{ end }}">
 <a {{ with $ref }} href="{{.}}" {{ end }} {{ with $target }} target="{{.}}" {{ end }} class="gdoc-button__link">
-    {{ $.Inner }}
+  {{ $.Inner }}
 </a>
 </span>
diff --git a/layouts/shortcodes/columns.html b/layouts/shortcodes/columns.html
index 4d474b8..ce92aee 100644
--- a/layouts/shortcodes/columns.html
+++ b/layouts/shortcodes/columns.html
@@ -1,7 +1,7 @@
 <div class="gdoc-columns flex flex-wrap">
-    {{ range split .Inner "<--->" }}
-    <div class="gdoc-columns__content gdoc-markdown--nested flex-even">
-        {{ . | markdownify }}
-    </div>
-    {{ end }}
+  {{ range split .Inner "<--->" }}
+  <div class="gdoc-columns__content gdoc-markdown--nested flex-even">
+    {{ . | markdownify }}
+  </div>
+  {{ end }}
 </div>
diff --git a/layouts/shortcodes/expand.html b/layouts/shortcodes/expand.html
index 0be90c2..f3b67c9 100644
--- a/layouts/shortcodes/expand.html
+++ b/layouts/shortcodes/expand.html
@@ -1,12 +1,12 @@
 <div class="gdoc-expand">
-    <label>
-        <div class="gdoc-expand__head flex justify-between">
-            <span>{{ default "Expand" (.Get 0) }}</span>
-            <span>{{ default "↕" (.Get 1) }}</span>
-        </div>
-        <input type="checkbox" class="gdoc-expand__control hidden" />
-        <div class="gdoc-markdown--nested gdoc-expand__content">
-            {{ .Inner | markdownify }}
-        </div>
-    </label>
+  <label>
+    <div class="gdoc-expand__head flex justify-between">
+      <span>{{ default "Expand" (.Get 0) }}</span>
+      <span>{{ default "↕" (.Get 1) }}</span>
+    </div>
+    <input type="checkbox" class="gdoc-expand__control hidden" />
+    <div class="gdoc-markdown--nested gdoc-expand__content">
+      {{ .Inner | markdownify }}
+    </div>
+  </label>
 </div>
diff --git a/layouts/shortcodes/hint.html b/layouts/shortcodes/hint.html
index 8bf8ce1..5506853 100644
--- a/layouts/shortcodes/hint.html
+++ b/layouts/shortcodes/hint.html
@@ -1,3 +1,3 @@
 <blockquote class="gdoc-hint {{ .Get 0 }}">
-    {{ .Inner | markdownify }}
+  {{ .Inner | markdownify }}
 </blockquote>
diff --git a/layouts/shortcodes/mermaid.html b/layouts/shortcodes/mermaid.html
index 3948eca..d144c6a 100644
--- a/layouts/shortcodes/mermaid.html
+++ b/layouts/shortcodes/mermaid.html
@@ -1,9 +1,14 @@
 {{ if not (.Page.Scratch.Get "mermaid") }}
 <!-- Include mermaid only first time -->
 <script src="{{ "js/mermaid.min.js" | relURL }}"></script>
+<script>
+  mermaid.initialize({
+    flowchart: { useMaxWidth: true }
+  });
+</script>
 {{ .Page.Scratch.Set "mermaid" true }}
 {{ end }}
 
 <p class="mermaid{{ with .Get "class" }} {{ . }}{{ end }}">
-    {{ .Inner }}
+  {{- .Inner -}}
 </p>
diff --git a/layouts/shortcodes/tab.html b/layouts/shortcodes/tab.html
index 9c162e7..e2a207c 100644
--- a/layouts/shortcodes/tab.html
+++ b/layouts/shortcodes/tab.html
@@ -1,12 +1,12 @@
 {{ if .Parent }}
-    {{ $name := .Get 0 }}
-    {{ $group := printf "tabs-%s" (.Parent.Get 0) }}
+  {{ $name := .Get 0 }}
+  {{ $group := printf "tabs-%s" (.Parent.Get 0) }}
 
-    {{ if not (.Parent.Scratch.Get $group) }}
-        {{ .Parent.Scratch.Set $group slice }}
-    {{ end }}
+  {{ if not (.Parent.Scratch.Get $group) }}
+    {{ .Parent.Scratch.Set $group slice }}
+  {{ end }}
 
-    {{ .Parent.Scratch.Add $group (dict "Name" $name "Content" .Inner) }}
+  {{ .Parent.Scratch.Add $group (dict "Name" $name "Content" .Inner) }}
 {{ else }}
-    {{ errorf "%q: 'tab' shortcode must be inside 'tabs' shortcode" .Page.Path }}
+  {{ errorf "%q: 'tab' shortcode must be inside 'tabs' shortcode" .Page.Path }}
 {{ end}}
diff --git a/layouts/shortcodes/tabs.html b/layouts/shortcodes/tabs.html
index 2ab4d1f..fb9965a 100644
--- a/layouts/shortcodes/tabs.html
+++ b/layouts/shortcodes/tabs.html
@@ -3,14 +3,14 @@
 {{ $group := printf "tabs-%s" $id }}
 
 <div class="gdoc-tabs">
-    {{ range $index, $tab :=  .Scratch.Get $group }}
-        <input type="radio" class="gdoc-tabs__control hidden" name="{{ $group }}" id="{{ printf "%s-%d" $group $index }}"
-            {{ if not $index }}checked="checked" {{ end }} />
-        <label for="{{ printf "%s-%d" $group $index }}" class="gdoc-tabs__label">
-            {{ $tab.Name }}
-        </label>
-        <div class="gdoc-markdown--nested gdoc-tabs__content">
-            {{ .Content | markdownify }}
-        </div>
-    {{ end }}
+  {{ range $index, $tab :=  .Scratch.Get $group }}
+    <input type="radio" class="gdoc-tabs__control hidden" name="{{ $group }}" id="{{ printf "%s-%d" $group $index }}"
+      {{ if not $index }}checked="checked" {{ end }} />
+    <label for="{{ printf "%s-%d" $group $index }}" class="gdoc-tabs__label">
+      {{ $tab.Name }}
+    </label>
+    <div class="gdoc-markdown--nested gdoc-tabs__content">
+      {{ .Content | markdownify }}
+    </div>
+  {{ end }}
 </div>
diff --git a/layouts/shortcodes/toc-tree.html b/layouts/shortcodes/toc-tree.html
index 7fe4620..310bd5a 100644
--- a/layouts/shortcodes/toc-tree.html
+++ b/layouts/shortcodes/toc-tree.html
@@ -1,35 +1,33 @@
 {{ $tocLevels := default (default 6 .Site.Params.GeekdocToC) .Page.Params.GeekdocToC }}
 
 {{ if $tocLevels }}
-    <div class="gdoc-toc gdoc-toc__level--{{$tocLevels}}">
-        {{ template "toc-tree" dict "sect" .Page.Pages }}
-    </div>
+  <div class="gdoc-toc gdoc-toc__level--{{$tocLevels}}">
+    {{ template "toc-tree" dict "sect" .Page.Pages }}
+  </div>
 {{ end }}
 
 <!-- templates -->
 {{ define "toc-tree" }}
-    <ul>
-        {{ range .sect.GroupBy "Weight" }}
-            {{ range .ByTitle }}
-            {{ if not .Params.geekdocHidden }}
-            <li>
-            {{ if or .Content .Params.geekdocFlatSection }}
-                <span>
-                    <a href="{{ .RelPermalink }}" class="gdoc-toc__entry">
-                        {{ partial "title" . }}
-                    </a>
-                </span>
-            {{ else }}
-                <span>{{ partial "title" . }}</span>
-            {{ end }}
+  <ul>
+    {{ range .sect.GroupBy "Weight" }}
+      {{ range .ByTitle }}
+      {{ if not .Params.geekdocHidden }}
+      <li>
+      {{ if or .Content .Params.geekdocFlatSection }}
+        <span>
+          <a href="{{ .RelPermalink }}" class="gdoc-toc__entry">{{ partial "title" . }}</a>
+        </span>
+      {{ else }}
+        <span>{{ partial "title" . }}</span>
+      {{ end }}
 
-            {{ $numberOfPages := (add (len .Pages) (len .Sections)) }}
-            {{ if and (ne $numberOfPages 0) (not .Params.geekdocFlatSection) }}
-                {{ template "toc-tree" dict "sect" .Pages }}
-            {{ end }}
-            </li>
-            {{ end }}
-            {{ end }}
-        {{ end }}
-    </ul>
+      {{ $numberOfPages := (add (len .Pages) (len .Sections)) }}
+      {{ if and (ne $numberOfPages 0) (not .Params.geekdocFlatSection) }}
+        {{ template "toc-tree" dict "sect" .Pages }}
+      {{ end }}
+      </li>
+      {{ end }}
+      {{ end }}
+    {{ end }}
+  </ul>
 {{ end }}
diff --git a/layouts/shortcodes/toc.html b/layouts/shortcodes/toc.html
index b1c64e9..771478f 100644
--- a/layouts/shortcodes/toc.html
+++ b/layouts/shortcodes/toc.html
@@ -1,8 +1,5 @@
 {{ $tocLevels := default (default 6 .Site.Params.GeekdocToC) .Page.Params.GeekdocToC }}
 
 {{ if and $tocLevels .Page.TableOfContents }}
-    <div class="gdoc-toc gdoc-toc__level--{{$tocLevels}}">
-        {{ .Page.TableOfContents }}
-        <hr>
-    </div>
+  <div class="gdoc-toc gdoc-toc__level--{{$tocLevels}}">{{ .Page.TableOfContents }}<hr></div>
 {{ end }}