Improve milestone page UI

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/pages/milestone.scss

@@ -28,7 +28,7 @@ li.milestone {
 
     // Issue title
     span a {
-      color: rgba(0,0,0,0.64);
+      color: $gl-text-color;
     }
   }
 }
@@ -51,7 +51,7 @@ li.milestone {
     margin-top: 7px;
 
     .issuable-number {
-      color: rgba(0,0,0,0.44);
+      color: $gl-placeholder-color;
       margin-right: 5px;
     }
     .avatar {

app/views/projects/milestones/show.html.haml

@@ -24,15 +24,15 @@
       - else
         = link_to 'Reopen Milestone', namespace_project_milestone_path(@project.namespace, @project, @milestone, milestone: {state_event: :activate }), method: :put, class: "btn btn-reopen btn-nr btn-grouped"
 
-      = link_to namespace_project_milestone_path(@project.namespace, @project, @milestone), data: { confirm: 'Are you sure?' }, method: :delete, class: "btn btn-grouped btn-nr" do
-        = icon('trash-o')
-        Delete
-
       = link_to edit_namespace_project_milestone_path(@project.namespace, @project, @milestone), class: "btn btn-grouped btn-nr" do
         = icon('pencil-square-o')
         Edit
 
-.detail-page-description.milestone-detail.second-block
+      = link_to namespace_project_milestone_path(@project.namespace, @project, @milestone), data: { confirm: 'Are you sure?' }, method: :delete, class: "btn btn-grouped btn-danger" do
+        = icon('trash-o')
+        Delete
+
+.detail-page-description.milestone-detail
   %h2.title
     = markdown escape_once(@milestone.title), pipeline: :single_line
   %div

app/views/shared/milestones/_top.html.haml

@@ -24,7 +24,7 @@
         - else
           = link_to 'Reopen Milestone', group_milestone_path(group, milestone.safe_title, title: milestone.title, milestone: {state_event: :activate }), method: :put, class: "btn btn-grouped btn-reopen"
 
-.detail-page-description.gray-content-block.second-block
+.detail-page-description.milestone-detail
   %h2.title
     = markdown escape_once(milestone.title), pipeline: :single_line