Added UX improvements

app/assets/stylesheets/pages/members.scss

@@ -98,6 +98,10 @@
     padding-right: 35px;
 
     @media (min-width: $screen-sm-min) {
+      width: 250px;
+    }
+
+    @media (min-width: $screen-md-min) {
       width: 350px;
     }
 

app/views/projects/project_members/_new_project_member.html.haml

 = form_for @project_member, as: :project_member, url: namespace_project_project_members_path(@project.namespace, @project), html: { class: 'users-project-form' } do |f|
-  .row
-    .col-md-5.col-lg-5
+  .form-group
     = users_select_tag(:user_ids, multiple: true, class: "input-clamp", scope: :all, email_user: true, placeholder: "Search for members to update or invite")
     .help-block.append-bottom-10
       Search for members by name, username, or email, or invite new ones using their email address.
-
-    .col-md-2.col-lg-2
+  .form-group
     = select_tag :access_level, options_for_select(ProjectMember.access_level_roles, @project_member.access_level), class: "form-control project-access-select"
     .help-block.append-bottom-10
       = link_to "Read more", help_page_path("user/permissions"), class: "vlink"
       about role permissions
-
-    .col-md-2
+  .form-group
     .clearable-input
       = text_field_tag :expires_at, nil, class: 'form-control js-access-expiration-date', placeholder: 'Expiration date'
       %i.clear-icon.js-clear-input
     .help-block.append-bottom-10
       On this date, the member(s) will automatically lose access to this project.
-
-    .col-md-2
-      = f.submit "Add to project", class: "btn btn-create btn-block"
-    .col-md-1
+  = f.submit "Add to project", class: "btn btn-create"
   = link_to "Import", import_namespace_project_project_members_path(@project.namespace, @project), class: "btn btn-default hidden-xs hidden-sm pull-right", title: "Import members from another project"