diff --git a/src/application/views/appointments/book.php b/src/application/views/appointments/book.php
index 495764a0..26ad91d7 100644
--- a/src/application/views/appointments/book.php
+++ b/src/application/views/appointments/book.php
@@ -90,7 +90,7 @@
                                     <strong><?= lang('select_service') ?></strong>
                                 </label>
 
-                                <select id="select-service" class="col-md-4 form-control">
+                                <select id="select-service" class="col-xs-12 col-sm-4 form-control">
                                     <?php
                                         // Group services by category, only if there is at least one service with a parent category.
                                         $has_category = FALSE;
@@ -150,7 +150,7 @@
                                     <strong><?= lang('select_provider') ?></strong>
                                 </label>
 
-                                <select id="select-provider" class="col-md-4 form-control"></select>
+                                <select id="select-provider" class="col-xs-12 col-sm-4 form-control"></select>
                             </div>
 
                             <div id="service-description" style="display:none;"></div>
@@ -272,7 +272,7 @@
                         </div>
                         <?php if ($this->settings_model->get_setting('require_captcha') === '1'): ?>
                         <div class="frame-content row">
-                            <div class="col-sm-12 col-md-6">
+                            <div class="col-xs-12 col-sm-6">
                                 <h4 class="captcha-title">
                                     CAPTCHA
                                     <small class="glyphicon glyphicon-refresh"></small>
diff --git a/src/application/views/backend/calendar.php b/src/application/views/backend/calendar.php
index f1c963c0..97451637 100644
--- a/src/application/views/backend/calendar.php
+++ b/src/application/views/backend/calendar.php
@@ -37,7 +37,7 @@
 
 <div id="calendar-page" class="container-fluid">
     <div id="calendar-toolbar">
-        <div id="calendar-filter" class="form-inline col-xs-12 col-md-5">
+        <div id="calendar-filter" class="form-inline col-xs-12 col-sm-5">
             <div class="form-group">
                 <label for="select-filter-item"><?= lang('display_calendar') ?></label>
                 <select id="select-filter-item" class="form-control" title="<?= lang('select_filter_item_hint') ?>">
diff --git a/src/application/views/backend/settings.php b/src/application/views/backend/settings.php
index bf3ba29b..76144f03 100644
--- a/src/application/views/backend/settings.php
+++ b/src/application/views/backend/settings.php
@@ -69,7 +69,7 @@
                     </legend>
 
                     <div class="wrapper row">
-                        <div class="col-md-6">
+                        <div class="col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="company-name"><?= lang('company_name') ?> *</label>
                                 <input id="company-name" data-field="company_name" class="required form-control">
@@ -94,7 +94,7 @@
                                 </span>
                             </div>
                         </div>
-                        <div class="col-md-6">
+                        <div class="col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="google-analytics-code">
                                     Google Analytics ID</label>
@@ -165,7 +165,7 @@
                     </legend>
 
                     <div class="row">
-                        <div class="col-md-7 working-plan-wrapper">
+                        <div class="col-xs-12 col-sm-7 working-plan-wrapper">
                             <h4><?= lang('working_plan') ?></h4>
                             <span class="help-block">
                                 <?= lang('edit_working_plan_hint') ?>
@@ -278,7 +278,7 @@
                                 <input id="book-advance-timeout" data-field="book_advance_timeout" class="form-control">
                             </div>
                         </div>
-                        <div class="col-md-5 breaks-wrapper">
+                        <div class="col-xs-12 col-sm-5 breaks-wrapper">
                             <h4><?= lang('breaks') ?></h4>
 
                             <span class="help-block">
diff --git a/src/application/views/backend/users.php b/src/application/views/backend/users.php
index ee50dc42..c9496a36 100644
--- a/src/application/views/backend/users.php
+++ b/src/application/views/backend/users.php
@@ -100,7 +100,7 @@
                     <input type="hidden" id="admin-id" class="record-id">
 
                     <div class="row">
-                        <div class="admin-details col-md-6">
+                        <div class="admin-details col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="first-name"><?= lang('first_name') ?> *</label>
                                 <input id="admin-first-name" class="form-control required" maxlength="256">
@@ -151,7 +151,7 @@
                                 <textarea id="admin-notes" class="form-control" rows="3"></textarea>
                             </div>
                         </div>
-                        <div class="admin-settings col-md-6">
+                        <div class="admin-settings col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="admin-username"><?= lang('username') ?> *</label>
                                 <input id="admin-username" class="form-control required" maxlength="256">
@@ -253,7 +253,7 @@
                         <input type="hidden" id="provider-id" class="record-id">
 
                         <div class="row">
-                            <div class="provider-details col-md-6">
+                            <div class="provider-details col-xs-12 col-sm-6">
                                 <div class="form-group">
                                     <label for="provider-first-name"><?= lang('first_name') ?> *</label>
                                     <input id="provider-first-name" class="form-control required" maxlength="256">
@@ -304,7 +304,7 @@
                                     <textarea id="provider-notes" class="form-control" rows="3"></textarea>
                                 </div>
                             </div>
-                            <div class="provider-settings col-md-6">
+                            <div class="provider-settings col-xs-12 col-sm-6">
                                 <div class="form-group">
                                     <label for="provider-username"><?= lang('username') ?> *</label>
                                     <input id="provider-username" class="form-control required" maxlength="256">
@@ -538,7 +538,7 @@
                     <input type="hidden" id="secretary-id" class="record-id">
 
                     <div class="row">
-                        <div class="secretary-details col-md-6">
+                        <div class="secretary-details col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="secretary-first-name"><?= lang('first_name') ?> *</label>
                                 <input id="secretary-first-name" class="form-control required" maxlength="256">
@@ -589,7 +589,7 @@
                                 <textarea id="secretary-notes" class="form-control" rows="3"></textarea>
                             </div>
                         </div>
-                        <div class="secretary-settings col-md-6">
+                        <div class="secretary-settings col-xs-12 col-sm-6">
                             <div class="form-group">
                                 <label for="secretary-username"><?= lang('username') ?> *</label>
                                 <input id="secretary-username" class="form-control required" maxlength="256">
diff --git a/src/application/views/general/installation.php b/src/application/views/general/installation.php
index 0f2a494c..f4c10bf2 100755
--- a/src/application/views/general/installation.php
+++ b/src/application/views/general/installation.php
@@ -80,7 +80,7 @@
         <div class="alert hidden"></div>
 
         <div class="row">
-            <div class="admin-settings col-md-5">
+            <div class="admin-settings col-xs-12 col-sm-5">
                 <h3>Administrator</h3>
 
                 <div class="form-group">
@@ -119,7 +119,7 @@
                 </div>
             </div>
 
-            <div class="company-settings col-md-5">
+            <div class="company-settings col-xs-12 col-sm-5">
                 <h3>Company</h3>
 
                 <div class="form-group">
diff --git a/src/assets/js/backend_users.js b/src/assets/js/backend_users.js
index 500a6554..5a5dd156 100644
--- a/src/assets/js/backend_users.js
+++ b/src/assets/js/backend_users.js
@@ -148,7 +148,7 @@ window.BackendUsers = window.BackendUsers || {};
 
                     $('#secretary-providers').data('jsp').destroy();
 
-                    var html = '<div class="col-md-12">';
+                    var html = '<div class="col-xs-12">';
                     $.each(GlobalVariables.providers, function(index, provider) {
                        html +=
                             '<div class="checkbox">' +