diff --git a/back_to_top.module b/back_to_top.module
index 2acd362..4b09141 100644
--- a/back_to_top.module
+++ b/back_to_top.module
@@ -1,5 +1,11 @@
 <?php
 
+/**
+ * @file
+ * Contains back_to_top.module.
+ */
+
+use Drupal\Core\Routing\RouteMatchInterface;
 
 /**
  * Implements hook_page_attachments().
@@ -7,12 +13,12 @@
 function back_to_top_page_attachments(array &$attachments) {
   $config = \Drupal::config('back_to_top.settings');
   $settings = $config->get();
-  $button_settings = array(
+  $button_settings = [
     'back_to_top_prevent_on_mobile' => $settings['back_to_top_prevent_on_mobile'],
     'back_to_top_prevent_in_admin' => $settings['back_to_top_prevent_in_admin'],
     'back_to_top_button_type' => $settings['back_to_top_button_type'],
     'back_to_top_button_text' => $settings['back_to_top_button_text'],
-  );
+  ];
   if ($settings['back_to_top_prevent_on_mobile'] && (is_mobile())) {
     return FALSE;
   }
@@ -20,18 +26,15 @@ function back_to_top_page_attachments(array &$attachments) {
     return FALSE;
   }
   if ($settings['back_to_top_prevent_in_front'] && (\Drupal::service('path.matcher')
-      ->isFrontPage())
+    ->isFrontPage())
   ) {
     return FALSE;
   }
 
-  //$attachments['#attached']['library'][] = 'core/jquery.ui.core';
-  //$attachments['#attached']['library'][] = 'core/jquery.ui.effects.core';
-
   $attachments['#attached']['library'][] = 'back_to_top/back_to_top_js';
   $attachments['#attached']['drupalSettings']['back_to_top']['back_to_top_button_trigger'] = $settings['back_to_top_button_trigger'];
 
-  // Add stylesheet for image or text/css button
+  // Add stylesheet for image or text/css button.
   if (($settings['back_to_top_button_type']) == "text") {
     $attachments['#attached']['library'][] = 'back_to_top/back_to_top_text';
   }
@@ -41,7 +44,7 @@ function back_to_top_page_attachments(array &$attachments) {
 
   $css = '';
   $hover_css = '';
-  // Check variables and add placement
+  // Check variables and add placement.
   if ($settings['back_to_top_button_place'] == 2) {
     $css .= "left: 10px;";
   }
@@ -66,15 +69,15 @@ function back_to_top_page_attachments(array &$attachments) {
   if ($settings['back_to_top_button_place'] == 9) {
     $css .= "top: 50%; left: 50%; margin-left: -50px;";
   }
-  // Check variables and add color from settings - this code could be done a bit nicer
+  // Check variables and add color from settings - this code could be done a bit nicer.
   if (($settings['back_to_top_button_type'] == "text") && ($settings['back_to_top_bg_color'] !== '#F7F7F7')) {
     $css .= "background: " . $settings['back_to_top_bg_color'] . ";";
   }
   if (($settings['back_to_top_button_type'] == "text") && ($settings['back_to_top_border_color'] !== '#CCCCCC')) {
-    $css .= "border-color: " . $settings['back_to_top_bg_color'] . ";";
+    $css .= "border-color: " . $settings['back_to_top_border_color'] . ";";
   }
   if (($settings['back_to_top_button_type'] == "text") && ($settings['back_to_top_hover_color'] !== '#EEEEEE')) {
-    $hover_css .= "#backtotop:hover { background: " . $settings['back_to_top_hover_color'] . "; border-color: " . $settings['back_to_top_hover_color'] . "; }";
+    $hover_css .= "#backtotop:hover { background: " . $settings['back_to_top_hover_color'] . "; border-color: " . $settings['back_to_top_border_color'] . "; }";
   }
   if (($settings['back_to_top_button_type'] == "text") && ($settings['back_to_top_text_color'] !== '#333333')) {
     $css .= "color: " . $settings['back_to_top_text_color'] . ";";
@@ -84,18 +87,20 @@ function back_to_top_page_attachments(array &$attachments) {
     $attachments['#attached']['html_head'][] = [
       [
         '#tag' => 'style',
-        '#value' => '#backtotop {' . $css . '}' . $hover_css,
+        '#value' => 'body #backtotop {' . $css . '}' . $hover_css,
       ],
-      'css'
+      'css',
     ];
   }
 
-  // Add settings to js
+  // Add settings to js.
   $attachments['#attached']['drupalSettings']['back_to_top'] += $button_settings;
 }
 
 /**
- * Check if mobile or touch device with PHP so javascript and css isn't included in that case
+ * Check if mobile or touch device with PHP.
+ *
+ * So javascript and css isn't included in that case.
  */
 function is_mobile() {
   // Check for mobile device using Browscap module if it is available.
@@ -113,7 +118,7 @@ function is_mobile() {
     return TRUE;
   }
   if (isset($_SERVER["HTTP_USER_AGENT"])) {
-    $user_agents = array(
+    $user_agents = [
       "midp",
       "j2me",
       "iphone",
@@ -183,8 +188,8 @@ function is_mobile() {
       "ipad",
       "android",
       "ipod",
-      "webos"
-    );
+      "webos",
+    ];
 
     foreach ($user_agents as $user_string) {
       if (preg_match("/" . $user_string . "/i", strtolower($_SERVER["HTTP_USER_AGENT"]))) {
@@ -196,7 +201,9 @@ function is_mobile() {
 }
 
 /**
- * Check if page viewed is in admin section or a node/edit for possible option to not include javascript and css in that case
+ * Check if page viewed is in admin section or a node/edit for possible option.
+ *
+ * To not include javascript and css in that case.
  */
 function is_adminpage() {
   $route = \Drupal::routeMatch()->getRouteObject();
@@ -211,11 +218,11 @@ function is_adminpage() {
 /**
  * Implements hook_help().
  */
-function back_to_top_help($route_name, \Drupal\Core\Routing\RouteMatchInterface $route_match) {
+function back_to_top_help($route_name, RouteMatchInterface $route_match) {
   switch ($route_name) {
     case 'help.page.back_to_top':
       $text = file_get_contents(dirname(__FILE__) . "/README.txt");
-      if (! \Drupal::moduleHandler()->moduleExists('markdown')) {
+      if (!\Drupal::moduleHandler()->moduleExists('markdown')) {
         return '<pre>' . $text . '</pre>';
       }
       else {