Improve email notification styling

Add `enhanced_notify_css` feature flag. When enabled, use the main
GitLab UI framework to style email notifications.

Changelog: changed

app/assets/stylesheets/framework/mixins.scss

@@ -439,6 +439,12 @@
       .na {
         color: inherit;
       }
+
+      // Rouge `Comment` token (quoted text in email body)
+      .c {
+        color: $gl-grayish-blue;
+        font-style: italic;
+      }
     }
   }
 }

app/assets/stylesheets/notify.scss

-@import 'framework/mixins';
-@import 'framework/variables';
-
-img {
-  max-width: 100%;
-  height: auto;
-}
-
-p.details {
-  font-style: italic;
-  color: $gray-500;
-}
-
-.footer > p {
-  font-size: small;
-  color: $gray-500;
-}
-
-pre.commit-message {
-  white-space: pre-wrap;
-}
+@import 'notify_base';
 
 .gl-label-scoped {
   border: 2px solid currentColor;
@@ -47,6 +27,4 @@ pre.commit-message {
     border: 1px solid $gray-100;
     border-radius: $border-radius-small;
   }
-
-  @include email-code-block;
 }

app/assets/stylesheets/notify_base.scss

+@import 'framework/mixins';
+@import 'framework/variables';
+
+img {
+  max-width: 100%;
+  height: auto;
+}
+
+p.details {
+  font-style: italic;
+  color: $gray-500;
+}
+
+.footer > p {
+  font-size: small;
+  color: $gray-500;
+}
+
+pre.commit-message {
+  white-space: pre-wrap;
+}
+
+.content {
+  @include email-code-block;
+}

app/assets/stylesheets/notify_enhanced.scss

+// Import a subset of the GitLab UI framework:
+// keep parts that affect elements that can appear in emails;
+// omit Bootstrap Reboot since it adds unnecessary styles to every element.
+@import 'notify_base';
+@import 'bootstrap/scss/functions';
+@import 'bootstrap/scss/variables';
+@import 'bootstrap/scss/mixins';
+@import 'bootstrap/scss/code';
+@import '@gitlab/ui/src/scss/variables';
+@import '@gitlab/ui/src/scss/utility-mixins/index';
+@import '@gitlab/ui/src/scss/components';
+@import 'bootstrap_migration';
+@import 'framework/common';
+@import 'framework/gfm';
+@import 'framework/kbd';
+@import 'framework/tables';
+@import 'framework/typography';
+@import 'framework/emojis';
+
+body {
+  font-family: $regular-font;
+  font-size: inherit;
+}
+
+a {
+  text-decoration: none;
+}
+
+.content {
+  .md {
+    padding: 1rem 0;
+  }
+
+  hr {
+    border: 1px solid #e1e1e1;
+  }
+
+  blockquote {
+    border-top-width: 0;
+    border-bottom-width: 0;
+    border-right-width: 0;
+
+    &:dir(rtl) {
+      border-left-width: 0;
+      border-right-width: inherit;
+    }
+  }
+
+  table {
+    border-collapse: collapse;
+  }
+
+  .diff-table.code,
+  table.code {
+    width: auto;
+
+    td {
+      padding: inherit;
+
+      pre {
+        background-color: inherit;
+        margin: 0;
+        padding: 0;
+        border: inherit;
+      }
+    }
+  }
+}

app/views/layouts/notify.html.haml

@@ -3,6 +3,9 @@
     %meta{ content: "text/html; charset=utf-8", "http-equiv" => "Content-Type" }
     %title
       GitLab
+    - if Feature.enabled?(:enhanced_notify_css)
+      = stylesheet_link_tag 'notify_enhanced'
+    - else
       = stylesheet_link_tag 'notify'
     = yield :head
   %body

app/views/layouts/service_desk.html.haml

@@ -5,6 +5,9 @@
     %title
       GitLab
     -# haml-lint:enable NoPlainNodes
+    - if Feature.enabled?(:enhanced_notify_css)
+      = stylesheet_link_tag 'notify_enhanced'
+    - else
       = stylesheet_link_tag 'notify'
     = yield :head
   %body

app/views/notify/_note_email.html.haml

@@ -25,11 +25,11 @@
   = content_for :head do
     = stylesheet_link_tag 'mailers/highlighted_diff_email'
 
-  %table
+  %table.code
     = render partial: "projects/diffs/email_line",
       collection: discussion.truncated_diff_lines(diff_limit: diff_limit),
       as: :line,
       locals: { diff_file: discussion.diff_file }
 
-%div{ style: note_style }
+.md{ style: note_style }
   = markdown(note.note, pipeline: :email, author: note.author, current_user: @recipient, issuable_reference_expansion_enabled: true)

app/views/notify/issue_due_email.html.haml

@@ -8,5 +8,5 @@
   This issue is due on: #{@issue.due_date.to_s(:medium)}
 
 - if @issue.description
-  %div
+  .md
     = markdown(@issue.description, pipeline: :email, author: @issue.author, current_user: @recipient, issuable_reference_expansion_enabled: true)

app/views/notify/new_issue_email.html.haml

@@ -7,5 +7,5 @@
     = assignees_label(@issue)
 
 - if @issue.description
-  %div
+  .md
     = markdown(@issue.description, pipeline: :email, author: @issue.author, current_user: @recipient, issuable_reference_expansion_enabled: true)

app/views/notify/new_merge_request_email.html.haml

@@ -15,5 +15,5 @@
     = render_if_exists 'notify/merge_request_approvers', presenter: @mr_presenter
 
 - if @merge_request.description
-  %div
+  .md
     = markdown(@merge_request.description, pipeline: :email, author: @merge_request.author, current_user: @recipient, issuable_reference_expansion_enabled: true)

app/views/notify/new_release_email.html.haml

 - release_link_start = '<a href="%{url}" target="_blank" rel="noopener noreferrer">'.html_safe % { url: @target_url }
 - description_details = { tag: @release.tag, name: @project.name, release_link_start: release_link_start, release_link_end: '</a>'.html_safe }
 
-%div{ style: "font-family: 'Helvetica Neue',Helvetica,Arial,sans-serif;" }
+.md{ style: "font-family: 'Helvetica Neue',Helvetica,Arial,sans-serif;" }
   %p
     = _("A new Release %{tag} for %{name} was published. Visit the %{release_link_start}Releases page%{release_link_end} to read more about it.").html_safe % description_details
 

app/views/notify/service_desk_new_note_email.html.haml

 - if Gitlab::CurrentSettings.email_author_in_body
   %div
     = _("%{author_link} wrote:").html_safe % { author_link: link_to(@note.author_name, user_url(@note.author)) }
-%div
+.md
   = markdown(@note.note, pipeline: :email, author: @note.author, issuable_reference_expansion_enabled: true)

config/application.rb

@@ -247,6 +247,7 @@ module Gitlab
     config.assets.precompile << "mailer.css"
     config.assets.precompile << "mailer_client_specific.css"
     config.assets.precompile << "notify.css"
+    config.assets.precompile << "notify_enhanced.css"
     config.assets.precompile << "mailers/*.css"
     config.assets.precompile << "page_bundles/_mixins_and_variables_and_functions.css"
     config.assets.precompile << "page_bundles/admin/application_settings_metrics_and_profiling.css"

config/feature_flags/development/enhanced_notify_css.yml

+---
+name: enhanced_notify_css
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/78604
+rollout_issue_url:
+milestone: '14.8'
+type: development
+group: group::project management
+default_enabled: false

ee/app/views/notify/add_merge_request_approver_email.html.haml

@@ -14,5 +14,5 @@
     = render 'notify/merge_request_approvers', presenter: @mr_presenter
 
 - if @merge_request.description
-  %div
+  .md
     = markdown(@merge_request.description, pipeline: :email, author: @merge_request.author, current_user: @recipient, issuable_reference_expansion_enabled: true)

ee/app/views/notify/new_epic_email.html.haml

@@ -7,5 +7,5 @@
     = assignees_label(@epic)
 
 - if @epic.description
-  %div
+  .md
     = markdown(@epic.description, pipeline: :email, author: @epic.author, current_user: @recipient, issuable_reference_expansion_enabled: true)