Update markup in file

app/views/clusters/clusters/_gcp_signup_offer_banner.html.haml

 - link = link_to(s_('ClusterIntegration|sign up'), 'https://console.cloud.google.com/freetrial?utm_campaign=2018_cpanel&utm_source=gitlab&utm_medium=referral', target: '_blank', rel: 'noopener noreferrer')
 .gcp-signup-offer.gl-alert.gl-alert-info.gl-my-3{ role: 'alert', data: { feature_id: UserCalloutsHelper::GCP_SIGNUP_OFFER, dismiss_endpoint: user_callouts_path } }
-  %button.js-close.gl-alert-dismiss{ type: 'button', 'aria-label' => _('Dismiss') }
-    = sprite_icon('close', size: 16, css_class: 'gl-icon')
-  = sprite_icon('information-o', size: 16, css_class: 'gl-icon gl-alert-icon gl-alert-icon-no-title')
-  %h4.gl-alert-title= s_('ClusterIntegration|Did you know?')
-  %p.gl-alert-body= s_('ClusterIntegration|Every new Google Cloud Platform (GCP) account receives $300 in credit upon %{sign_up_link}. In partnership with Google, GitLab is able to offer an additional $200 for both new and existing GCP accounts to get started with GitLab\'s Google Kubernetes Engine Integration.').html_safe % { sign_up_link: link }
-  %a.gl-button.btn-confirm.text-decoration-none{ href: 'https://cloud.google.com/partners/partnercredit/?pcn_code=0014M00001h35gDQAQ#contact-form', target: '_blank', rel: 'noopener noreferrer' }
-    = s_("ClusterIntegration|Apply for credit")
+  .gl-alert-container
+    %button.js-close.btn.gl-dismiss-btn.btn-default.btn-sm.gl-button.btn-default-tertiary.btn-icon{ type: 'button', 'aria-label' => _('Dismiss') }
+      = sprite_icon('close', size: 16, css_class: 'gl-icon')
+    = sprite_icon('information-o', size: 16, css_class: 'gl-icon gl-alert-icon gl-alert-icon-no-title')
+    .gl-alert-content
+      %h4.gl-alert-title= s_('ClusterIntegration|Did you know?')
+      %p.gl-alert-body= s_('ClusterIntegration|Every new Google Cloud Platform (GCP) account receives $300 in credit upon %{sign_up_link}. In partnership with Google, GitLab is able to offer an additional $200 for both new and existing GCP accounts to get started with GitLab\'s Google Kubernetes Engine Integration.').html_safe % { sign_up_link: link }
+      %a.gl-button.btn-confirm.text-decoration-none{ href: 'https://cloud.google.com/partners/partnercredit/?pcn_code=0014M00001h35gDQAQ#contact-form', target: '_blank', rel: 'noopener noreferrer' }
+        = s_("ClusterIntegration|Apply for credit")