diff --git a/application/views/appointments/cookie_notice_modal.php b/application/views/appointments/cookie_notice_modal.php
index 37c5dc2a..007b87b4 100644
--- a/application/views/appointments/cookie_notice_modal.php
+++ b/application/views/appointments/cookie_notice_modal.php
@@ -1,9 +1,9 @@
-<div id="cookie-notice-modal" class="modal fade" tabindex="-1" role="dialog">
-    <div class="modal-dialog" role="document">
+<div id="cookie-notice-modal" class="modal fade" tabindex="-1">
+    <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
                 <h4 class="modal-title"><?= lang('cookie_notice') ?></h4>
-                <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+                <button type="button" class="close" data-dismiss="modal"><span>&times;</span></button>
             </div>
             <div class="modal-body">
                 <p><?= $cookie_notice_content ?></p>
diff --git a/application/views/appointments/privacy_policy_modal.php b/application/views/appointments/privacy_policy_modal.php
index fe489d38..ca5393fd 100644
--- a/application/views/appointments/privacy_policy_modal.php
+++ b/application/views/appointments/privacy_policy_modal.php
@@ -1,9 +1,9 @@
-<div id="privacy-policy-modal" class="modal fade" tabindex="-1" role="dialog">
-    <div class="modal-dialog" role="document">
+<div id="privacy-policy-modal" class="modal fade" tabindex="-1">
+    <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
                 <h4 class="modal-title"><?= lang('privacy_policy') ?></h4>
-                <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+                <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span></button>
             </div>
             <div class="modal-body">
                 <p><?= $privacy_policy_content ?></p>
diff --git a/application/views/appointments/terms_and_conditions_modal.php b/application/views/appointments/terms_and_conditions_modal.php
index 090e883f..a2208192 100644
--- a/application/views/appointments/terms_and_conditions_modal.php
+++ b/application/views/appointments/terms_and_conditions_modal.php
@@ -1,9 +1,9 @@
-<div id="terms-and-conditions-modal" class="modal fade" tabindex="-1" role="dialog">
-    <div class="modal-dialog" role="document">
+<div id="terms-and-conditions-modal" class="modal fade" tabindex="-1">
+    <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
                 <h4 class="modal-title"><?= lang('terms_and_conditions') ?></h4>
-                <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
+                <button type="button" class="close" data-dismiss="modal"><span aria-hidden="true">&times;</span></button>
             </div>
             <div class="modal-body">
                 <p><?= $terms_and_conditions_content ?></p>
diff --git a/application/views/backend/calendar.php b/application/views/backend/calendar.php
index 163738e5..82c23e3e 100755
--- a/application/views/backend/calendar.php
+++ b/application/views/backend/calendar.php
@@ -120,7 +120,7 @@
         <div class="modal-content">
             <div class="modal-header">
                 <h3 class="modal-title"><?= lang('edit_appointment_title') ?></h3>
-                <button class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
+                <button class="close" data-dismiss="modal">&times;</button>
             </div>
 
             <div class="modal-body">
@@ -344,7 +344,7 @@
         <div class="modal-content">
             <div class="modal-header">
                 <h3 class="modal-title"><?= lang('new_unavailable_title') ?></h3>
-                <button class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
+                <button class="close" data-dismiss="modal">&times;</button>
             </div>
             <div class="modal-body">
                 <div class="modal-message alert d-none"></div>
@@ -410,7 +410,7 @@
         <div class="modal-content">
             <div class="modal-header">
                 <h3 class="modal-title"><?= lang('new_extra_period_title') ?></h3>
-                <button class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
+                <button class="close" data-dismiss="modal">&times;</button>
             </div>
             <div class="modal-body">
                 <div class="modal-message alert d-none"></div>
@@ -469,7 +469,7 @@
     <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
-                <button class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
+                <button class="close" data-dismiss="modal">&times;</button>
                 <h3 class="modal-title"><?= lang('select_google_calendar') ?></h3>
             </div>
             <div class="modal-body">
diff --git a/application/views/backend/header.php b/application/views/backend/header.php
index 1aae0db5..0be468ed 100755
--- a/application/views/backend/header.php
+++ b/application/views/backend/header.php
@@ -38,8 +38,7 @@
         <span>EASY!APPOINTMENTS</span>
     </div>
 
-    <button type="button" class="navbar-toggler" data-toggle="collapse" data-target="#header-menu"
-            aria-expanded="false" aria-controls="navbar">
+    <button type="button" class="navbar-toggler" data-toggle="collapse" data-target="#header-menu">
         <span class="sr-only">Toggle navigation</span>
         <span class="navbar-toggler-icon"></span>
     </button>
diff --git a/application/views/backend/services.php b/application/views/backend/services.php
index 3d62046e..94eff1dd 100755
--- a/application/views/backend/services.php
+++ b/application/views/backend/services.php
@@ -25,16 +25,24 @@
 </script>
 
 <div class="container-fluid backend-page" id="services-page">
-    <ul class="nav nav-pills" role="tablist">
-        <li role="presentation" class="nav-item"><a class="nav-link active" href="#services" aria-controls="services" role="tab" data-toggle="tab"><?= lang('services') ?></a></li>
-        <li role="presentation" class="nav-item"><a class="nav-link" href="#categories" aria-controls="categories" role="tab" data-toggle="tab"><?= lang('categories') ?></a></li>
+    <ul class="nav nav-pills">
+        <li class="nav-item">
+            <a class="nav-link active" href="#services" data-toggle="tab">
+                <?= lang('services') ?>
+            </a>
+        </li>
+        <li class="nav-item">
+            <a class="nav-link" href="#categories" data-toggle="tab">
+                <?= lang('categories') ?>
+            </a>
+        </li>
     </ul>
 
     <div class="tab-content">
 
         <!-- SERVICES TAB -->
 
-        <div role="tabpanel" class="tab-pane active" id="services">
+        <div class="tab-pane active" id="services">
             <div class="row">
                 <div id="filter-services" class="filter-records col col-12 col-md-5">
                     <form class="mb-4">
@@ -154,7 +162,7 @@
 
         <!-- CATEGORIES TAB -->
 
-        <div role="tabpanel" class="tab-pane" id="categories">
+        <div class="tab-pane" id="categories">
             <div class="row">
                 <div id="filter-categories" class="filter-records column col-12 col-md-5">
                     <form class="input-append mb-4">
diff --git a/application/views/backend/settings.php b/application/views/backend/settings.php
index 9c0aa7d3..45801612 100755
--- a/application/views/backend/settings.php
+++ b/application/views/backend/settings.php
@@ -32,29 +32,29 @@
 </script>
 
 <div id="settings-page" class="container-fluid backend-page">
-    <ul class="nav nav-pills" role="tablist">
+    <ul class="nav nav-pills">
         <?php if ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE): ?>
-            <li role="presentation" class="nav-item">
-                <a class="nav-link" href="#general" aria-controls="general" role="tab" data-toggle="tab"><?= lang('general') ?></a>
+            <li class="nav-item">
+                <a class="nav-link" href="#general" data-toggle="tab"><?= lang('general') ?></a>
             </li>
         <?php endif ?>
         <?php if ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE): ?>
-            <li role="presentation" class="nav-item">
-                <a class="nav-link" href="#business-logic" aria-controls="business-logic" role="tab" data-toggle="tab"><?= lang('business_logic') ?></a>
+            <li class="nav-item">
+                <a class="nav-link" href="#business-logic" data-toggle="tab"><?= lang('business_logic') ?></a>
             </li>
         <?php endif ?>
         <?php if ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE): ?>
-            <li role="presentation" class="nav-item">
-                <a class="nav-link" href="#legal-contents" aria-controls="legal-contents" role="tab" data-toggle="tab"><?= lang('legal_contents') ?></a>
+            <li class="nav-item">
+                <a class="nav-link" href="#legal-contents" data-toggle="tab"><?= lang('legal_contents') ?></a>
             </li>
         <?php endif ?>
         <?php if ($privileges[PRIV_USER_SETTINGS]['view'] == TRUE): ?>
-            <li role="presentation" class="nav-item">
-                <a class="nav-link" href="#current-user" aria-controls="current-user" role="tab" data-toggle="tab"><?= lang('current_user') ?></a>
+            <li class="nav-item">
+                <a class="nav-link" href="#current-user" data-toggle="tab"><?= lang('current_user') ?></a>
             </li>
         <?php endif ?>
-        <li role="presentation" class="nav-item">
-            <a class="nav-link" href="#about-app" aria-controls="about-app" role="tab" data-toggle="tab"><?= lang('about_app') ?></a>
+        <li class="nav-item">
+            <a class="nav-link" href="#about-app" data-toggle="tab"><?= lang('about_app') ?></a>
         </li>
     </ul>
 
@@ -63,7 +63,7 @@
         <!-- GENERAL TAB -->
 
         <?php $hidden = ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE) ? '' : 'd-none' ?>
-        <div role="tabpanel" class="tab-pane active <?= $hidden ?>" id="general">
+        <div class="tab-pane active <?= $hidden ?>" id="general">
             <form>
                 <fieldset>
                     <legend class="border-bottom mb-4">
@@ -168,7 +168,7 @@
                             <div class="form-group">
                                 <label><?= lang('customer_notifications') ?></label>
                                 <br>
-                                <button type="button" id="customer-notifications" class="btn btn-light" data-toggle="button" aria-pressed="false">
+                                <button type="button" id="customer-notifications" class="btn btn-light" data-toggle="button">
                                     <i class="far fa-envelope"></i>
                                     <?= lang('receive_notifications') ?>
                                 </button>
@@ -181,7 +181,7 @@
                                     CAPTCHA
                                 </label>
                                 <br>
-                                <button type="button" id="require-captcha" class="btn btn-light" data-toggle="button" aria-pressed="false">
+                                <button type="button" id="require-captcha" class="btn btn-light" data-toggle="button">
                                     <i class="fas fa-lock"></i>
                                     <?= lang('require_captcha') ?>
                                 </button>
@@ -194,7 +194,7 @@
                                     <?= lang('phone_number') ?>
                                 </label>
                                 <br>
-                                <button type="button" id="require-phone-number" class="btn btn-light" data-toggle="button" aria-pressed="false">
+                                <button type="button" id="require-phone-number" class="btn btn-light" data-toggle="button">
                                     <i class="fas fa-phone-alt"></i>
                                     <?= lang('require_phone_number') ?>
                                 </button>
@@ -205,7 +205,7 @@
                             <div class="form-group">
                                 <label><?= lang('any_provider') ?></label>
                                 <br>
-                                <button type="button" id="display-any-provider" class="btn btn-light" data-toggle="button" aria-pressed="false">
+                                <button type="button" id="display-any-provider" class="btn btn-light" data-toggle="button">
                                     <i class="fas fa-user"></i>
                                     <?= lang('display_any_provider') ?>
                                 </button>
@@ -222,7 +222,7 @@
         <!-- BUSINESS LOGIC TAB -->
 
         <?php $hidden = ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE) ? '' : 'd-none' ?>
-        <div role="tabpanel" class="tab-pane <?= $hidden ?>" id="business-logic">
+        <div class="tab-pane <?= $hidden ?>" id="business-logic">
             <form>
                 <fieldset>
                     <legend class="border-bottom mb-4">
@@ -308,7 +308,7 @@
         <!-- LEGAL CONTENTS TAB -->
 
         <?php $hidden = ($privileges[PRIV_SYSTEM_SETTINGS]['view'] == TRUE) ? '' : 'd-none' ?>
-        <div role="tabpanel" class="tab-pane <?= $hidden ?>" id="legal-contents">
+        <div class="tab-pane <?= $hidden ?>" id="legal-contents">
             <form>
                 <fieldset>
                     <legend class="border-bottom mb-4">
@@ -386,7 +386,7 @@
         <!-- CURRENT USER TAB -->
 
         <?php $hidden = ($privileges[PRIV_USER_SETTINGS]['view'] == TRUE) ? '' : 'd-none' ?>
-        <div role="tabpanel" class="tab-pane <?= $hidden ?>" id="current-user">
+        <div class="tab-pane <?= $hidden ?>" id="current-user">
             <form>
                 <div class="row">
                     <fieldset class="col-12 col-sm-6 personal-info-wrapper">
@@ -496,7 +496,7 @@
 
         <!-- ABOUT TAB -->
 
-        <div role="tabpanel" class="tab-pane" id="about-app">
+        <div class="tab-pane" id="about-app">
             <h3>Easy!Appointments</h3>
 
             <p>
diff --git a/application/views/backend/users.php b/application/views/backend/users.php
index 60ef4022..c509f04a 100755
--- a/application/views/backend/users.php
+++ b/application/views/backend/users.php
@@ -36,17 +36,29 @@
 <div class="container-fluid backend-page" id="users-page">
 
     <!-- PAGE NAVIGATION -->
-    <ul class="nav nav-pills" role="tablist">
-        <li role="presentation" class="nav-item"><a class="nav-link active" href="#providers" aria-controls="providers" role="tab" data-toggle="tab"><?= lang('providers') ?></a></li>
-        <li role="presentation" class="nav-item"><a class="nav-link" href="#secretaries" aria-controls="secretaries" role="tab" data-toggle="tab"><?= lang('secretaries') ?></a></li>
-        <li role="presentation" class="nav-item"><a class="nav-link" href="#admins" aria-controls="admins" role="tab" data-toggle="tab"><?= lang('admins') ?></a></li>
+    <ul class="nav nav-pills">
+        <li class="nav-item">
+            <a class="nav-link active" href="#providers" data-toggle="tab">
+                <?= lang('providers') ?>
+            </a>
+        </li>
+        <li class="nav-item">
+            <a class="nav-link" href="#secretaries" data-toggle="tab">
+                <?= lang('secretaries') ?>
+            </a>
+        </li>
+        <li class="nav-item">
+            <a class="nav-link" href="#admins" data-toggle="tab">
+                <?= lang('admins') ?>
+            </a>
+        </li>
     </ul>
 
     <div class="tab-content">
 
         <!-- PROVIDERS TAB -->
 
-        <div role="tabpanel" class="tab-pane active" id="providers">
+        <div class="tab-pane active" id="providers">
             <div class="row">
                 <div id="filter-providers" class="filter-records column col-12 col-md-5">
                     <form class="mb-4">
@@ -291,7 +303,7 @@
 
         <!-- SECRETARIES TAB -->
 
-        <div role="tabpanel" class="tab-pane" id="secretaries">
+        <div class="tab-pane" id="secretaries">
             <div class="row">
                 <div id="filter-secretaries" class="filter-records column col-12 col-md-5">
                     <form class="mb-4">
@@ -451,7 +463,7 @@
 
         <!-- ADMINS TAB -->
 
-        <div role="tabpanel" class="tab-pane" id="admins">
+        <div class="tab-pane" id="admins">
             <div class="row">
                 <div id="filter-admins" class="filter-records column col-12 col-md-5">
                     <form class="mb-4">