diff --git a/composer.json b/composer.json
index 7c282a4..f6e7a81 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,8 @@
         }
     },
     "require": {
-        "drupal/core": "^9 || ^10"
+        "drupal/core": "^9 || ^10",
+        "drupal/twig_real_content": "^1.0"
     },
     "require-dev": {},
     "minimum-stability": "dev",
diff --git a/includes/preprocess.html.inc b/includes/preprocess.html.inc
index 61328a9..d8cd242 100644
--- a/includes/preprocess.html.inc
+++ b/includes/preprocess.html.inc
@@ -9,6 +9,31 @@
  * Implements hook_preprocess_HOOK() for html.html.twig.
  */
 function kiso_preprocess_html(&$variables) {
+
+  $variables['page_navigation'] = _kiso_render_region($variables['page']['navigation']);
+  $variables['page_complementary'] = _kiso_render_region($variables['page']['complementary']);
+  $has_navigation = _kiso_has_region($variables['page_navigation']);
+  $has_complementary = _kiso_has_region($variables['page_complementary']);
+
+  // Added body classes when sidebar(s) has (have) content.
+  if ($has_navigation && $has_complementary) {
+    $variables['attributes']['class'][] = 'sidebar';
+    $variables['attributes']['class'][] = 'two-sidebars';
+  }
+  elseif ($has_navigation) {
+    $variables['attributes']['class'][] = 'sidebar';
+    $variables['attributes']['class'][] = 'one-sidebar';
+    $variables['attributes']['class'][] = 'is-visible--navigation';
+  }
+  elseif ($has_complementary) {
+    $variables['attributes']['class'][] = 'sidebar';
+    $variables['attributes']['class'][] = 'one-sidebar';
+    $variables['attributes']['class'][] = 'is-visible--complementary';
+  }
+  else {
+    $variables['attributes']['class'][] = 'no-sidebars';
+  }
+
   // Add body classes related to node content.
   $node = \Drupal::routeMatch()->getParameter('node');
   if ($node) {
diff --git a/includes/preprocess.page.inc b/includes/preprocess.page.inc
index 50f37a5..908333d 100644
--- a/includes/preprocess.page.inc
+++ b/includes/preprocess.page.inc
@@ -9,6 +9,14 @@
  * Implements hook_preprocess_HOOK() for page.html.twig.
  */
 function kiso_preprocess_page(&$variables) {
+  // Add boolean variables detecting if regions are empty.
+  $theme = \Drupal::theme()->getActiveTheme()->getName();
+  $regions = system_region_list($theme);
+  foreach ($regions as $key => $value) {
+    $variables['page_'. $key] = _kiso_render_region($variables['page'][$key]);
+    $variables['has_' . $key] = _kiso_has_region($variables['page_'. $key]);
+  }
+
   // Create variable for status code.
   if ($exception = \Drupal::request()->get('exception')) {
     $status_code = $exception->getStatusCode();
diff --git a/includes/preprocess.utils.inc b/includes/preprocess.utils.inc
index b3e6f4d..3ce4afe 100644
--- a/includes/preprocess.utils.inc
+++ b/includes/preprocess.utils.inc
@@ -1,14 +1,94 @@
 <?php
 
+use Twig\TwigFilter;
+
+/**
+ * Small function to render the regions without passing them by reference.
+ *
+ * @param $region
+ *
+ * @return mixed
+ */
+function _kiso_render_region($region) {
+  return Drupal::service('renderer')->render($region);
+}
+
 /**
  * @file
  * Utilities used by the theme preprocess functions.
  */
 
+/**
+ * Properly detect if regions are empty.
+ *
+ * @param ?string $markup
+ *   The rendered region markup to be tested if empty.
+ * @param string $allowed_tags
+ *   Allowed tags to be excluded from the strip HTML tags process.
+ *
+ * @return
+ *   TRUE if the region exists and is not empty, FALSE otherwise.
+ *
+ * @see https://www.drupal.org/node/953034
+ * @see https://drupal.stackexchange.com/questions/175389/how-do-i-properly-detect-if-region-is-empty
+ */
+function _kiso_has_region(?string $markup, string $allowed_tags = '') {
+  $moduleHandler = Drupal::service('module_handler');
+  if ($moduleHandler->moduleExists('twig_real_content')) {
+    $filters = Drupal::service('twig_real_content.twig_extension')
+      ->getFilters();
+    $key = array_search('real_content', array_map(function(TwigFilter $filter) {
+      return $filter->getName();
+    }, $filters), TRUE);
+    $callable = $filters[$key]->getCallable();
+
+    $real_content = $callable($markup);
+
+    return !empty($real_content);
+  }
+  else {
+    $non_conditional_html_comments_pattern = '/<!--(.|\s)*?-->\s*|\r|\n/';
+    $cleaned_region_output = preg_replace($non_conditional_html_comments_pattern, '', $markup);
+
+    return !empty(_kiso_strip_tags($cleaned_region_output, $allowed_tags));
+  }
+}
+
 /**
  * Strips html tags, except allowed, returning a trimmed clean markup.
+ *
+ * @param string $markup
+ *  Original markup.
+ * @param string|array $allowed_tags
+ *  Allowed tags, can be an array of tag of a string.
+ *
+ * @return string
+ * @throws \Twig\Error\RuntimeError
  */
-function _kiso_strip_tags(string $markup, string $allowed_tags = '') {
-  $allowed_tags .= '<drupal-render-placeholder><img>';
-  return trim(strip_tags($markup, $allowed_tags));
+function _kiso_strip_tags(string $markup, string|array $allowed_tags) {
+  $allowed_tags_base = [
+    '<drupal-render-placeholder>',
+    '<embed>',
+    '<hr>',
+    '<iframe>',
+    '<img>',
+    '<input>',
+    '<link>',
+    '<object>',
+    '<script>',
+    '<source>',
+    '<style>',
+    '<video>',
+  ];
+
+  if (is_string($allowed_tags)) {
+    $allowed_tags .= implode('', $allowed_tags_base);
+  }
+  elseif (is_array($allowed_tags)) {
+    $allowed_tags = array_merge($allowed_tags_base, $allowed_tags);
+  }
+
+  $text = strip_tags($markup, $allowed_tags);
+  $text = twig_trim_filter($text);
+  return $text;
 }
diff --git a/templates/layout/html.html.twig b/templates/layout/html.html.twig
index c9be4e7..5796f45 100644
--- a/templates/layout/html.html.twig
+++ b/templates/layout/html.html.twig
@@ -27,17 +27,6 @@
     db_offline ? 'db-offline',
   ]
 %}
-{% set page_navigaton = page.navigation|render %}
-{% set page_complementary = page.complementary|render %}
-{% if page_navigation is real_content and page_complementary is real_content %}
-  {% set body_classes = body_classes|merge(['sidebar', 'two-sidebars']) %}
-{% elseif page_navigaton is real_content %}
-  {% set body_classes = body_classes|merge(['sidebar', 'one-sidebar', 'is-visible--navigation']) %}
-{% elseif page_complementary is real_content %}
-  {% set body_classes = body_classes|merge(['sidebar', 'one-sidebar', 'is-visible--complementary']) %}
-{% else %}
-  {% set body_classes = body_classes|merge(['no-sidebars']) %}
-{% endif %}
 {# Enable the "Back to top" button. #}
 {% if backtotop_enable %}
   {% set attributes = attributes.setAttribute('id', 'top') %}
diff --git a/templates/layout/page.html.twig b/templates/layout/page.html.twig
index 364328d..aa46f36 100644
--- a/templates/layout/page.html.twig
+++ b/templates/layout/page.html.twig
@@ -8,6 +8,10 @@
  *
  * You will find same variables as in the core 'page.html.twig' template.
  *
+ * Custom variables:
+ * - has_tools, has_header, has_header_collapsible, has_highlighted, has_navigation,
+ *   has_complementary, has_postscript, has_footer: Properly detect if regions are empty.
+ *
  * Regions:
  * - page.tools: Items for the Toolbar region.
  * - page.header: Items for the Header region.
@@ -36,36 +40,36 @@
 {% set container = container_fluid ? 'container-fluid' : 'container' %}
 
 {# Toolbar Area #}
-{% if page.tools|render is real_content %}
+{% if has_tools %}
   {% block tools %}
     <div class="page__wrapper page__wrapper--tools">
       <div class="page__section page__section--tools {{ container }}">
-        {{ page.tools }}
+        {{ page_tools }}
       </div>
     </div>
   {% endblock %}
 {% endif %}
 
 {# Banner Landmark #}
-{% if page.header|render is real_content or page.header_collapsible|render is real_content %}
+{% if has_header or has_header_collapsible %}
   {% block header %}
     <div class="page__wrapper page__wrapper--header">
       <header class="page__section page__section--header {{ container }}">
-        {{ page.header }}
+        {{ page_header }}
         {# This button is used as the toggle for the Header (Collapsible) #}
         <button type="button" class="button button--toggler" aria-controls="headerCollapsible" aria-expanded="false"><span>Menu</span></button>
-        {{ page.header_collapsible }}
+        {{ page_header_collapsible }}
       </header>
     </div>
   {% endblock %}
 {% endif %}
 
 {# Featured content Area #}
-{% if page.highlighted|render is real_content %}
+{% if has_highlighted %}
   {% block highlighted %}
     <div class="page__wrapper page__wrapper--highlighted">
       <div class="page__section page__section--highlighted {{ container }}">
-        {{ page.highlighted }}
+        {{ page_highlighted }}
       </div>
     </div>
   {% endblock %}
@@ -77,15 +81,15 @@
 
     {# Dynamic help text #}
     {% block help %}
-      {{ page.help }}
+      {{ page_help }}
     {% endblock %}
 
     {# Breadcrumb #}
     {% block breadcrumb %}
-      {{ page.breadcrumb }}
+      {{ page_breadcrumb }}
     {% endblock %}
 
-    {% if page.navigation|render is real_content or page.complementary|render is real_content %}
+    {% if has_navigation or has_complementary %}
       <div class="{{ container }}">
         <div class="row">
     {% endif %}
@@ -95,12 +99,12 @@
         set content_classes = [
           'page__section',
           'page__section--content',
-          page.navigation|render is real_content or page.complementary|render is real_content ? '' : container,
+          has_navigation or has_complementary ? '' : container,
         ]
       %}
       {% block content %}
         <main{{ content_attributes.addClass(content_classes).setAttribute('role', 'main') }}>
-          {{ page.content }}
+          {{ page_content }}
 
           {# Enable and display the "Back to top" button. #}
           {% if backtotop_enable %}
@@ -110,24 +114,24 @@
       {% endblock %}
 
       {# Navigation sidebar (Left) #}
-      {% if page.navigation|render is real_content %}
+      {% if has_navigation %}
         {% block navigation %}
           <div class="page__section page__section--navigation">
-            {{ page.navigation }}
+            {{ page_navigation }}
           </div>
         {% endblock %}
       {% endif %}
 
       {# Related content sidebar (Right) #}
-      {% if page.complementary|render is real_content %}
+      {% if has_complementary %}
         {% block complementary %}
           <div class="page__section page__section--complementary">
-            {{ page.complementary }}
+            {{ page_complementary }}
           </div>
         {% endblock %}
       {% endif %}
 
-    {% if page.navigation|render is real_content or page.complementary|render is real_content %}
+    {% if has_navigation or has_complementary %}
         </div>
       </div>
     {% endif %}
@@ -136,22 +140,22 @@
 {% endblock %}
 
 {# Footnotes Area #}
-{% if page.postscript|render is real_content %}
+{% if has_postscript %}
   {% block postscript %}
     <div class="page__wrapper page__wrapper--postscript">
       <div class="page__section page__section--postscript {{ container }}">
-        {{ page.postscript }}
+        {{ page_postscript }}
       </div>
     </div>
   {% endblock %}
 {% endif %}
 
 {# Contentinfo Landmark #}
-{% if page.footer|render is real_content %}
+{% if has_footer %}
   {% block footer %}
     <div class="page__wrapper page__wrapper--footer">
       <footer class="page__section page__section--footer {{ container }}">
-        {{ page.footer }}
+        {{ page_footer }}
       </footer>
     </div>
   {% endblock %}