Restyle the Sessions#new view

app/assets/stylesheets/management/_forms.css.scss

@@ -1,3 +1,16 @@
+.centered_form {
+    @extend .col-md-4;
+    @extend .col-md-offset-4;
+    @extend .col-sm-6;
+    @extend .col-sm-offset-3;
+
+    input[type=submit] {
+        @extend .btn;
+        @extend .btn-primary;
+        @extend .btn-block;
+    }
+}
+
 select.date, select.datetime, select.time {
     display: inline;
     width: auto;

app/views/devise/sessions/new.html.slim

@@ -1,8 +1,11 @@
 - content_for(:title) { t 'sessions.sign_in' }
 
-h2.entry-title = t :login
-
-= simple_form_for(resource, as: resource_name, url: session_path(resource_name), ) do |f|
+.row
+  .centered_form
+    = simple_form_for(resource, as: resource_name, url: session_path(resource_name)) do |f|
+      header
+        legend
+          h2.entry-title = t 'sessions.sign_in_heading'
       .form-inputs
         = f.input :email, required: false, autofocus: true, hint: false
         = f.input :password, required: false, hint: false
@@ -11,4 +14,4 @@ h2.entry-title = t :login
       .form-actions
         = f.button :submit, t('sessions.sign_in')
 
-== render 'devise/shared/links'
+    = render 'devise/shared/links'