Improve HTML e-mails based on Litmus tests (#6301)

* Use PNG images in HTML e-mails

* Make webpack use URLs with host so fonts load inside HTML e-mails

Convert this back to a relative URL in the premailer CSS loader
since local requests are quicker

* Improve responsive design

* Add missing PNG icon

12 files changed, 19 insertions, 22 deletions

diff --git a/app/views/layouts/mailer.html.haml b/app/views/layouts/mailer.html.haml
index e41b91069..6687546fb 100644
--- a/app/views/layouts/mailer.html.haml
+++ b/app/views/layouts/mailer.html.haml
@@ -24,7 +24,7 @@
                               %tr
                                 %td.column-cell
                                   = link_to root_url do
-                                    = image_tag full_pack_url('logo_full.svg'), alt: 'Mastodon', height: 34, class: 'logo'
+                                    = image_tag full_pack_url('logo_full.png'), alt: 'Mastodon', height: 34, class: 'logo'
 
     = yield
 
@@ -41,15 +41,12 @@
                   %tr
                     %td.blank-cell.footer
                       .email-row
-                        .col-4
+                        .col-6
                           %table.column{ cellspacing: 0, cellpadding: 0 }
                             %tbody
                               %td.column-cell
                                 %p= t 'about.hosted_on', domain: site_hostname
                                 %p= link_to t('application_mailer.notification_preferences'), settings_notifications_url
-                        .col-2
-                          %table.column{ cellspacing: 0, cellpadding: 0 }
-                            %tbody
                               %td.column-cell.text-right
                                 = link_to root_url do
-                                  = image_tag full_pack_url('logo_transparent.svg'), alt: 'Mastodon', height: 24
+                                  = image_tag full_pack_url('logo_transparent.png'), alt: 'Mastodon', height: 24
diff --git a/app/views/notification_mailer/favourite.html.haml b/app/views/notification_mailer/favourite.html.haml
index f26b08b18..7d1b494d0 100644
--- a/app/views/notification_mailer/favourite.html.haml
+++ b/app/views/notification_mailer/favourite.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_grade.svg'), alt:''
+                                      = image_tag full_pack_url('icon_grade.png'), alt:''
 
                               %h1= t 'notification_mailer.favourite.title'
                               %p.lead= t('notification_mailer.favourite.body', name: @account.acct)
diff --git a/app/views/notification_mailer/follow.html.haml b/app/views/notification_mailer/follow.html.haml
index 1290e2bc4..31a2b7445 100644
--- a/app/views/notification_mailer/follow.html.haml
+++ b/app/views/notification_mailer/follow.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_person_add.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_person_add.png'), alt: ''
 
                               %h1= t 'notification_mailer.follow.title'
                               %p.lead= t('notification_mailer.follow.body', name: @account.acct)
diff --git a/app/views/notification_mailer/follow_request.html.haml b/app/views/notification_mailer/follow_request.html.haml
index 41efeafaf..44f1911c4 100644
--- a/app/views/notification_mailer/follow_request.html.haml
+++ b/app/views/notification_mailer/follow_request.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_person_add.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_person_add.png'), alt: ''
 
                               %h1= t 'notification_mailer.follow_request.title'
                               %p.lead= t('notification_mailer.follow_request.body', name: @account.acct)
diff --git a/app/views/notification_mailer/mention.html.haml b/app/views/notification_mailer/mention.html.haml
index 619c580ce..479fed41c 100644
--- a/app/views/notification_mailer/mention.html.haml
+++ b/app/views/notification_mailer/mention.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_reply.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_reply.png'), alt: ''
 
                               %h1= t 'notification_mailer.mention.title'
                               %p.lead= t('notification_mailer.mention.body', name: @status.account.acct)
diff --git a/app/views/notification_mailer/reblog.html.haml b/app/views/notification_mailer/reblog.html.haml
index 61c6ee6be..85b202cf9 100644
--- a/app/views/notification_mailer/reblog.html.haml
+++ b/app/views/notification_mailer/reblog.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_cached.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_cached.png'), alt: ''
 
                               %h1= t 'notification_mailer.reblog.title'
                               %p.lead= t('notification_mailer.reblog.body', name: @account.acct)
diff --git a/app/views/user_mailer/confirmation_instructions.html.haml b/app/views/user_mailer/confirmation_instructions.html.haml
index 0f999bcbc..1f088a16f 100644
--- a/app/views/user_mailer/confirmation_instructions.html.haml
+++ b/app/views/user_mailer/confirmation_instructions.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_email.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_email.png'), alt: ''
 
                               %h1= t 'devise.mailer.confirmation_instructions.title'
 
diff --git a/app/views/user_mailer/email_changed.html.haml b/app/views/user_mailer/email_changed.html.haml
index 45dc06650..7e82f23e4 100644
--- a/app/views/user_mailer/email_changed.html.haml
+++ b/app/views/user_mailer/email_changed.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_email.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_email.png'), alt: ''
 
                               %h1= t 'devise.mailer.email_changed.title'
                               %p.lead= t 'devise.mailer.email_changed.explanation'
diff --git a/app/views/user_mailer/password_change.html.haml b/app/views/user_mailer/password_change.html.haml
index 2e9377dff..26314a217 100644
--- a/app/views/user_mailer/password_change.html.haml
+++ b/app/views/user_mailer/password_change.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_lock_open.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_lock_open.png'), alt: ''
 
                               %h1= t 'devise.mailer.password_change.title'
                               %p.lead= t 'devise.mailer.password_change.explanation'
diff --git a/app/views/user_mailer/reconfirmation_instructions.html.haml b/app/views/user_mailer/reconfirmation_instructions.html.haml
index 3ae226093..e3be8e295 100644
--- a/app/views/user_mailer/reconfirmation_instructions.html.haml
+++ b/app/views/user_mailer/reconfirmation_instructions.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_email.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_email.png'), alt: ''
 
                               %h1= t 'devise.mailer.reconfirmation_instructions.title'
                               %p.lead= t 'devise.mailer.reconfirmation_instructions.explanation'
diff --git a/app/views/user_mailer/reset_password_instructions.html.haml b/app/views/user_mailer/reset_password_instructions.html.haml
index c0e6775d4..5d9ce6a75 100644
--- a/app/views/user_mailer/reset_password_instructions.html.haml
+++ b/app/views/user_mailer/reset_password_instructions.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_lock_open.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_lock_open.png'), alt: ''
 
                               %h1= t 'devise.mailer.reset_password_instructions.title'
                               %p.lead= t 'devise.mailer.reset_password_instructions.explanation'
diff --git a/app/views/user_mailer/welcome.html.haml b/app/views/user_mailer/welcome.html.haml
index 0823efa1a..d734da67d 100644
--- a/app/views/user_mailer/welcome.html.haml
+++ b/app/views/user_mailer/welcome.html.haml
@@ -17,7 +17,7 @@
                                 %tbody
                                   %tr
                                     %td
-                                      = image_tag full_pack_url('icon_done.svg'), alt: ''
+                                      = image_tag full_pack_url('icon_done.png'), alt: ''
 
                               %h1= t 'user_mailer.welcome.title', name: @resource.account.username
                               %p.lead= t 'user_mailer.welcome.explanation'
@@ -30,7 +30,7 @@
           %table.content-section{ cellspacing: 0, cellpadding: 0 }
             %tbody
               %tr
-                %td.content-cell
+                %td.content-cell.content-start
                   .email-row
                     .col-3
                       %table.column{ cellspacing: 0, cellpadding: 0 }
@@ -46,7 +46,7 @@
                       %table.column{ cellspacing: 0, cellpadding: 0 }
                         %tbody
                           %tr
-                            %td.column-cell.content-start
+                            %td.column-cell
                               %p= t 'user_mailer.welcome.full_handle_hint', instance: @instance
 
 %table.email-table{ cellspacing: 0, cellpadding: 0 }
@@ -69,7 +69,7 @@
                       %table.column{ cellspacing: 0, cellpadding: 0 }
                         %tbody
                           %tr
-                            %td.column-cell
+                            %td.column-cell.padded
                               %table.button.button-small{ align: 'left', cellspacing: 0, cellpadding: 0 }
                                 %tbody
                                   %tr
@@ -89,7 +89,7 @@
                       %table.column{ cellspacing: 0, cellpadding: 0 }
                         %tbody
                           %tr
-                            %td.column-cell
+                            %td.column-cell.padded
                               %table.button.button-small{ align: 'left', cellspacing: 0, cellpadding: 0 }
                                 %tbody
                                   %tr
@@ -109,7 +109,7 @@
                       %table.column{ cellspacing: 0, cellpadding: 0 }
                         %tbody
                           %tr
-                            %td.column-cell
+                            %td.column-cell.padded
                               %table.button.button-small{ align: 'left', cellspacing: 0, cellpadding: 0 }
                                 %tbody
                                   %tr