diff --git a/addons/mass_mailing/views/unsubscribe_templates.xml b/addons/mass_mailing/views/unsubscribe_templates.xml
index ad2c08416e3..2fe3e707321 100644
--- a/addons/mass_mailing/views/unsubscribe_templates.xml
+++ b/addons/mass_mailing/views/unsubscribe_templates.xml
@@ -22,7 +22,7 @@
                                 </div>
                             </div>
 
-                            <h1 class="page-header">Mailing Subscriptions</h1>
+                            <h1 class="o_page_header">Mailing Subscriptions</h1>
                             <p>Choose your mailing subscriptions</p>
                             <div id="div_opt_out">
                                 <ul class="list-group">
@@ -65,7 +65,7 @@
                 <input type="hidden" name="mailing_id" t-att-value="mailing_id"/>
                 <input type="hidden" name="res_id" t-att-value="res_id"/>
                 <div id="div_blacklist" class="col-lg-6 offset-lg-3">
-                    <h1 class="page-header">Mailing Subscriptions</h1>
+                    <h1 class="o_page_header">Mailing Subscriptions</h1>
 
                     <div id="subscription_info" class="alert alert-success text-center" role="status">
                         <p>You have been successfully <strong>unsubscribed</strong>!</p>
diff --git a/addons/portal/static/src/scss/portal.scss b/addons/portal/static/src/scss/portal.scss
index f76516a242f..a4ef0bb4775 100644
--- a/addons/portal/static/src/scss/portal.scss
+++ b/addons/portal/static/src/scss/portal.scss
@@ -147,6 +147,18 @@ hr {
     color: color-yiq($list-group-bg);
 }
 
+// Replaces old BS3 page-header class
+%o-page-header {
+    margin-bottom: $headings-margin-bottom * 2;
+    padding-bottom: $headings-margin-bottom;
+    border-bottom-width: $border-width;
+    border-bottom-style: solid;
+    border-bottom-color: $border-color;
+}
+.o_page_header {
+    @extend %o-page-header;
+}
+
 // Force table to their minimum width for fitting their col-*-auto parent
 .table.o_table_column_fit {
     width: 1px;
@@ -290,7 +302,7 @@ img.o_we_custom_image {
 }
 
 .o_portal_wrap {
-    .o_portal_my_home > .page-header > a:hover {
+    .o_portal_my_home > .o_page_header > a:hover {
         text-decoration: none;
     }
 
diff --git a/addons/portal/views/portal_templates.xml b/addons/portal/views/portal_templates.xml
index d9a98ef84d9..8e2c17fc9eb 100644
--- a/addons/portal/views/portal_templates.xml
+++ b/addons/portal/views/portal_templates.xml
@@ -93,7 +93,7 @@
                                     <t t-call="portal.portal_contact"/>
                                 </div>
                                 <div class="o_portal_my_details">
-                                    <h3 class="page-header">Your Details <a role="button" href="/my/account" class="btn btn-secondary btn-sm">Change</a></h3>
+                                    <h3 class="o_page_header">Your Details <a role="button" href="/my/account" class="btn btn-secondary btn-sm">Change</a></h3>
                                     <div t-field="user_id.partner_id" t-options='{"widget": "contact", "fields": ["email", "phone", "address", "name"]}'/>
                                 </div>
                                 <div class="o_my_archives" t-if="archive_groups">
@@ -126,7 +126,7 @@
             <t t-set="my_details" t-value="True"/>
             <div class="o_portal_my_home">
                 <div class="oe_structure"></div>
-                <h3 class="page-header">Your Documents</h3>
+                <h3 class="o_page_header">Your Documents</h3>
                 <ul class="o_portal_docs list-group">
                 </ul>
             </div>
@@ -243,7 +243,7 @@
     </template>
 
     <template id="portal_contact" name="Contact">
-        <h3 class="page-header"><t t-esc="title"/></h3>
+        <h3 class="o_page_header"><t t-esc="title"/></h3>
         <h5 t-esc="sales_user.name"/>
         <p><a t-att-href="'mailto:'+sales_user.email" t-esc="sales_user.email"/></p>
         <p t-esc="sales_user.phone"/>
@@ -251,7 +251,7 @@
     </template>
 
     <template id="portal_archive_groups" name="Portal Archive Groups">
-        <h3 class="page-header">Archives</h3>
+        <h3 class="o_page_header">Archives</h3>
         <ul class="nav nav-pills flex-column">
             <t t-foreach="archive_groups" t-as="group">
                 <t t-if="group['date_begin'] == date">
diff --git a/addons/project/views/project_rating_templates.xml b/addons/project/views/project_rating_templates.xml
index 05ccae166ee..af48d2506b3 100644
--- a/addons/project/views/project_rating_templates.xml
+++ b/addons/project/views/project_rating_templates.xml
@@ -154,7 +154,7 @@
                         <h1 t-esc="project.name" class="text-center"/>
                         <div class="row mb32">
                             <div>
-                                <h3 class="page-header">Customer Ratings</h3>
+                                <h3 class="o_page_header">Customer Ratings</h3>
                                 <div class="row">
                                     <div class="col-lg-7">
                                         <t t-foreach="ratings" t-as="rating">
diff --git a/addons/sale/views/sale_portal_templates.xml b/addons/sale/views/sale_portal_templates.xml
index ba8a13e3efa..de73eff2ba7 100644
--- a/addons/sale/views/sale_portal_templates.xml
+++ b/addons/sale/views/sale_portal_templates.xml
@@ -374,7 +374,7 @@
                     </t>
 
                     <div id="sale_order_communication">
-                        <h1 class="page-header">Communication</h1>
+                        <h1 class="o_page_header">Communication</h1>
                         <t t-call="portal.message_thread">
                             <t t-set="object" t-value="sale_order"/>
                         </t>
@@ -391,7 +391,7 @@
     -->
     <template id="sale_order_portal_content" name="Sales Order Portal Content">
         <!-- Intro -->
-        <div id="introduction" class="page-header mt16">
+        <div id="introduction" class="o_page_header mt16">
             <h1>
                 <span t-field="sale_order.type_name"></span>
                 <em t-esc="sale_order.name"/>
@@ -472,7 +472,7 @@
         </div>
 
         <section id="details" style="page-break-inside: auto;">
-            <h1 class="page-header" id="details">Details</h1>
+            <h1 class="o_page_header" id="details">Details</h1>
 
             <t t-set="display_discount" t-value="True in [line.discount > 0 for line in sale_order.order_line]"/>
 
@@ -619,7 +619,7 @@
         </section>
 
         <section id="terms" class="container" t-if="sale_order.note">
-            <h2 class="page-header">Terms &amp; Conditions</h2>
+            <h2 class="o_page_header">Terms &amp; Conditions</h2>
             <p t-field="sale_order.note"/>
         </section>
 
diff --git a/addons/sale_management/views/sale_portal_templates.xml b/addons/sale_management/views/sale_portal_templates.xml
index 616baafb3d8..64a056a8376 100644
--- a/addons/sale_management/views/sale_portal_templates.xml
+++ b/addons/sale_management/views/sale_portal_templates.xml
@@ -30,7 +30,7 @@
         <xpath expr="//section[@id='signature']" position="after">
             <t t-if="any([(not option.line_id) for option in sale_order.sale_order_option_ids])">
                 <section>
-                    <h1 class="page-header">Optional Products</h1>
+                    <h1 class="o_page_header">Optional Products</h1>
                     <t t-set="display_discount" t-value="True in [option.discount for option in sale_order.sale_order_option_ids]"/>
                     <table class="table table-hover">
                         <thead>
diff --git a/addons/sale_quotation_builder/data/sale_order_template_data.xml b/addons/sale_quotation_builder/data/sale_order_template_data.xml
index 829be772995..4a03ccbaac7 100644
--- a/addons/sale_quotation_builder/data/sale_order_template_data.xml
+++ b/addons/sale_quotation_builder/data/sale_order_template_data.xml
@@ -3,7 +3,7 @@
     <record id="sale_management.sale_order_template_default" model="sale.order.template">
         <field name="website_description" type="xml">
             <section data-snippet-id="title">
-                <h1 class="page-header">About us</h1>
+                <h1 class="o_page_header">About us</h1>
             </section>
             <section data-snippet-id="text-block">
                 <div class="row">
@@ -58,7 +58,7 @@
                 </div>
             </section>
             <section data-snippet-id="text-block">
-                <h1 class="page-header">Our Offer</h1>
+                <h1 class="o_page_header">Our Offer</h1>
                 <p>
                     You can <strong>set a description per product</strong>. Odoo will
                     automatically create a quotation using the descriptions
diff --git a/addons/survey/views/survey_templates.xml b/addons/survey/views/survey_templates.xml
index bd9657f79c8..1b8018a7473 100644
--- a/addons/survey/views/survey_templates.xml
+++ b/addons/survey/views/survey_templates.xml
@@ -172,7 +172,7 @@
 
     <!-- A page -->
     <template id="page" name="Page">
-        <div class="page-header">
+        <div class="o_page_header">
             <p class="float-right">Page <span t-raw='page_nr + 1'/> of <span t-raw="len(survey.page_ids)"/></p>
             <h1 t-field='page.title' />
             <div t-field='page.description' class="oe_no_empty"/>
@@ -343,7 +343,7 @@
                         </div>
                         <div role="form" class="js_surveyform" t-att-name="'%s' % (survey.id)" t-att-data-prefill="'/survey/prefill/%s/%s' % (slug(survey), token)">
                             <t t-foreach="survey.page_ids" t-as="page">
-                                <div class="page-header">
+                                <div class="o_page_header">
                                     <h1 t-field='page.title' />
                                     <t t-if="page.description"><div t-field='page.description' class="oe_no_empty"/></t>
                                 </div>
diff --git a/addons/website/static/src/scss/website.scss b/addons/website/static/src/scss/website.scss
index c061370e61a..09ba9772154 100644
--- a/addons/website/static/src/scss/website.scss
+++ b/addons/website/static/src/scss/website.scss
@@ -251,8 +251,7 @@ table.table_desc tr td {
         &:after  { margin: 0 -100% 0 $grid-gutter-width/2; }
     }
     .s_title_underlined {
-        padding-bottom: $grid-gutter-width/3;
-        border-bottom: 1px solid;
+        @extend %o-page-header;
     }
     .s_title_small_caps {
         font-variant: small-caps;
diff --git a/addons/website_event/views/event_templates.xml b/addons/website_event/views/event_templates.xml
index aeaa72123d2..cd00dc5ef91 100644
--- a/addons/website_event/views/event_templates.xml
+++ b/addons/website_event/views/event_templates.xml
@@ -519,7 +519,7 @@
                             <t t-set="counter_type" t-value="1"/>
                             <t t-set="counter" t-value="0"/>
                             <t t-foreach="tickets" t-as="ticket">
-                                <h4 class="page-header mt16">
+                                <h4 class="o_page_header mt16">
                                     <strong>
                                         Ticket Type #<t t-raw="counter_type"/>: <t t-esc="ticket['name']"/>
                                         <t t-if="ticket['price'] == 0">(Free)</t>
diff --git a/addons/website_event_questions/views/event_templates.xml b/addons/website_event_questions/views/event_templates.xml
index ba93593735e..cacaa567170 100644
--- a/addons/website_event_questions/views/event_templates.xml
+++ b/addons/website_event_questions/views/event_templates.xml
@@ -32,7 +32,7 @@
         <!-- Generic questions -->
         <xpath expr="//*[hasclass('modal-body')]/div/t[last()]" position="after">
             <t t-if="event.general_question_ids">
-                <h4 class="page-header mt8"><strong>Questions</strong></h4>
+                <h4 class="o_page_header mt8"><strong>Questions</strong></h4>
                 <div>
                     <div t-foreach='event.general_question_ids' t-as='question'>
                         <div class="row mb4">
diff --git a/addons/website_event_track/views/event_track_templates.xml b/addons/website_event_track/views/event_track_templates.xml
index 054721c3d36..677deb4c07b 100644
--- a/addons/website_event_track/views/event_track_templates.xml
+++ b/addons/website_event_track/views/event_track_templates.xml
@@ -55,7 +55,7 @@
         <section class="container" t-foreach="dayslist" t-as="day">
             <t t-set="locations" t-value="days[day]['locations']"/>
             <t t-set="dates" t-value="days[day]['dates']"/>
-            <h3 class="page-header mt0">
+            <h3 class="o_page_header mt0">
                 <span t-field="tracks_by_days[day][0].date" t-options="{'widget': 'date'}"/>
                 <small><t t-esc="len(tracks_by_days[day])"/> talks</small>
             </h3>
@@ -318,7 +318,7 @@
                 <div class="col-lg-8">
                     <div class="oe_structure">
                         <section>
-                            <h3 class="page-header mt16">
+                            <h3 class="o_page_header mt16">
                                 Introduction
                             </h3>
                             <p>
@@ -332,7 +332,7 @@
                             </p>
                         </section>
                         <section>
-                            <h3 class="page-header">Application</h3>
+                            <h3 class="o_page_header">Application</h3>
                             <p>
                                 Fill this form to propose your talk.
 
diff --git a/addons/website_forum/static/src/js/website_forum.js b/addons/website_forum/static/src/js/website_forum.js
index 3a14dda6c66..5731c56fdec 100644
--- a/addons/website_forum/static/src/js/website_forum.js
+++ b/addons/website_forum/static/src/js/website_forum.js
@@ -182,7 +182,7 @@ odoo.define('website_forum.website_forum', function (require) {
             })
             .done(function() {
                 var left = $('.o_js_validation_queue:visible').length;
-                var type = $('h2.page-header li.active a').data('type');
+                var type = $('h2.o_page_header li.active a').data('type');
                 $('#count_post').text(left);
                 $('#moderation_tools a[href*="/'+type+'_"]').find('strong').text(left);
             });
diff --git a/addons/website_forum/views/website_forum.xml b/addons/website_forum/views/website_forum.xml
index 27d3f266b88..4bf4e25e4bc 100644
--- a/addons/website_forum/views/website_forum.xml
+++ b/addons/website_forum/views/website_forum.xml
@@ -389,7 +389,7 @@
 <!-- Specific Forum Layout -->
 <template id="forum_index" name="Forum">
     <t t-call="website_forum.header">
-        <h2 class="page-header mt0">
+        <h2 class="o_page_header mt0">
             <t t-esc="question_count"/>
                 <span t-if="post_type not in ('link','question','discussion')"> Posts </span>
                 <span t-if="post_type == 'question'"> Questions</span>
@@ -1178,7 +1178,7 @@
 
 <template id="moderation_queue">
     <t t-call="website_forum.header">
-        <h2 class="page-header mt0">
+        <h2 class="o_page_header mt0">
             <t t-set="count_posts" t-value="len(posts_ids)"/>
             <span id='count_post' t-esc="count_posts"/>
             <span class="dropdown">
@@ -1352,7 +1352,7 @@
 
 <template id="user_detail_full">
     <t t-call="website_forum.header">
-        <h1 class="mt0 page-header">
+        <h1 class="o_page_header mt0">
             <span t-field="user.name"/>
             <small>profile</small>
         </h1>
diff --git a/addons/website_forum_doc/views/website_doc.xml b/addons/website_forum_doc/views/website_doc.xml
index a35855e57fb..00824929168 100644
--- a/addons/website_forum_doc/views/website_doc.xml
+++ b/addons/website_forum_doc/views/website_doc.xml
@@ -12,7 +12,7 @@
         <template id="toc" name="Documentation Index">
             <t t-set="level" t-value="level+1"/>
             <t t-foreach="titles" t-as="title">
-                <div t-attf-class="h#{str(level) + (level&lt;3 and ' page-header' or '')}">
+                <div t-attf-class="h#{str(level) + (level&lt;3 and ' o_page_header' or '')}">
                     <t t-esc="title.name"/>
                     <small t-if="len(title.post_ids)">
                         <t t-esc="len(title.post_ids)"/>
@@ -74,7 +74,7 @@
                 </section>
                 <section class="container">
                     <t t-set="level" t-value="toc and 1 or 0"/>
-                    <h1 class="page-header" t-if="toc">
+                    <h1 class="o_page_header" t-if="toc">
                         <t t-esc="toc.name"/>
                     </h1>
                     <t t-set="titles" t-value="sections"/>
@@ -117,7 +117,7 @@
                 <section class="container">
                     <div class="row">
                         <div class="col-md-9">
-                            <h1 class="page-header" t-field="post.name"/>
+                            <h1 class="o_page_header" t-field="post.name"/>
                             <blockquote class="oe_toc_content" t-if="bool(post.content)">
                                 <t t-raw="post.content"/>
                             </blockquote>
@@ -126,7 +126,7 @@
                                 <t t-raw="post.child_ids[0].content"/>
                             </t>
                             <div t-if="len(toc.post_ids)&gt;1">
-                                <h2 class="page-header">Related topics</h2>
+                                <h2 class="o_page_header">Related topics</h2>
                                 <ul>
                                     <t t-foreach="toc.post_ids" t-as="topic">
                                         <li t-if="post.id != topic.id">
@@ -175,7 +175,7 @@
         <template id="promote_question">
             <t t-call="website.layout">
                 <section class="container">
-                    <h1 class="page-header">Promote question to documentation</h1>
+                    <h1 class="o_page_header">Promote question to documentation</h1>
                     <p>
                         To be promoted in the official documentation the question
                         and answer must satisfy the following criteria:
@@ -225,7 +225,7 @@
                     </div>
                 </div>
                 <section class="container">
-                    <h2 class="page-header">Samples</h2>
+                    <h2 class="o_page_header">Samples</h2>
                     <div class="row">
                         <div class="col-md-6">
                             <h4>Good question titles</h4>
diff --git a/addons/website_links/views/website_links_graphs.xml b/addons/website_links/views/website_links_graphs.xml
index 4242437a8da..149a78a4f69 100644
--- a/addons/website_links/views/website_links_graphs.xml
+++ b/addons/website_links/views/website_links_graphs.xml
@@ -27,7 +27,7 @@
                         <input type="hidden" id="code" t-att-value="code" />
                         <input type="hidden" id="link_id" t-att-value="id" />
 
-                        <h1 class="page-header mt0"><t t-esc="title"/></h1>
+                        <h1 class="o_page_header mt0"><t t-esc="title"/></h1>
 
                         <div class="row">
                             <div class="col-md-8">
@@ -104,7 +104,7 @@
                             </div>
                         </div>
 
-                        <h1 class="page-header">Statistics
+                        <h1 class="o_page_header">Statistics
                             <small class="float-right d-none d-md-block mt16" id="filters">
                                 <ul class="nav nav-tabs nav-tabs-inline graph-tabs" role="tablist">
                                     <li class="nav-item"><a aria-controls="all_time_charts" href="#all_time_charts" class="nav-link active" role="tab" data-toggle="tab">All Time</a></li>
diff --git a/addons/website_links/views/website_links_template.xml b/addons/website_links/views/website_links_template.xml
index 5d0fbc223ad..d69bddf7d63 100644
--- a/addons/website_links/views/website_links_template.xml
+++ b/addons/website_links/views/website_links_template.xml
@@ -28,7 +28,7 @@
         <template id="create_shorten_url">
             <div class="o_website_links_create_tracked_url">
                 <div class="container">
-                    <h1 class="page-header">Link Tracker</h1>
+                    <h1 class="o_page_header">Link Tracker</h1>
                     <div class="notification"></div>
 
                     <div class="row">
@@ -85,7 +85,7 @@
                         </div>
                     </div>
 
-                    <h2 class="page-header">Your tracked links
+                    <h2 class="o_page_header">Your tracked links
                         <small class="float-right d-none d-md-block mt16" id="filters">
                             <ul class="nav nav-tabs nav-tabs-inline graph-tabs" role="tablist">
                                 <li class="nav-item"><a aria-controls="filter-newest-links" href="#" class="nav-link active" id="filter-newest-links" role="tab" data-toggle="tab">Newest</a></li>
diff --git a/addons/website_mail_channel/views/website_mail_channel_templates.xml b/addons/website_mail_channel/views/website_mail_channel_templates.xml
index 4bd8353e5b5..7b439bb0b91 100644
--- a/addons/website_mail_channel/views/website_mail_channel_templates.xml
+++ b/addons/website_mail_channel/views/website_mail_channel_templates.xml
@@ -237,7 +237,7 @@
                         </div>
                     </div>
                     <div t-if="message.child_ids" class="o_mg_replies">
-                        <h4 class="page-header">Follow-Ups</h4>
+                        <h4 class="o_page_header">Follow-Ups</h4>
                         <t t-call="website_mail_channel.messages_short">
                             <t t-set="messages" t-value="message.child_ids[:replies_per_page]"/>
                             <t t-set="msg_more_count" t-value="len(message.child_ids) - replies_per_page"/>
@@ -245,7 +245,7 @@
                         </t>
                     </div>
                     <div t-if="message.parent_id">
-                        <h4 class="page-header">Reference</h4>
+                        <h4 class="o_page_header">Reference</h4>
                         <t t-call="website_mail_channel.messages_short">
                             <t t-set="messages" t-value="[message.parent_id]"/>
                         </t>
diff --git a/addons/website_sale/views/templates.xml b/addons/website_sale/views/templates.xml
index fe80a30d1ef..ce404acc77c 100644
--- a/addons/website_sale/views/templates.xml
+++ b/addons/website_sale/views/templates.xml
@@ -1054,7 +1054,7 @@
                         <div class="col-12 col-xl order-xl-1 oe_cart">
                             <div class="row">
                                 <div class="col-lg-12">
-                                    <h3 class="page-header mt8">Billing Address</h3>
+                                    <h3 class="o_page_header mt8">Billing Address</h3>
                                 </div>
                                 <div class="col-lg-6 one_kanban">
                                     <t t-call="website_sale.address_kanban">
@@ -1067,7 +1067,7 @@
                             <t t-if="not only_services" groups="sale.group_delivery_invoice_address">
                                 <div class="row">
                                     <div class="col-lg-12">
-                                        <h3 class="page-header mt16 mb4">Shipping Address</h3>
+                                        <h3 class="o_page_header mt16 mb4">Shipping Address</h3>
                                     </div>
                                 </div>
                                 <div class="row all_shipping">
@@ -1162,16 +1162,16 @@
                         <div class="col-12 col-xl order-xl-1 oe_cart">
                             <div>
                                 <t t-if="mode == ('new', 'billing')">
-                                    <h2 class="page-header mt8">Your Address
+                                    <h2 class="o_page_header mt8">Your Address
                                         <small> or </small>
                                         <a role="button" href='/web/login?redirect=/shop/checkout' class='btn btn-primary' style="margin-top: -11px">Log In</a>
                                     </h2>
                                 </t>
                                 <t t-if="mode == ('edit', 'billing')">
-                                    <h2 class="page-header mt8">Your Address</h2>
+                                    <h2 class="o_page_header mt8">Your Address</h2>
                                 </t>
                                 <t t-if="mode[1] == 'shipping'">
-                                    <h2 class="page-header mt8">Shipping Address </h2>
+                                    <h2 class="o_page_header mt8">Shipping Address </h2>
                                 </t>
                                 <t t-if="error" t-foreach="error.get('error_message', [])" t-as="err">
                                     <h4 class="text-danger" t-esc="err" />