Add .alert-alt styling

services/web/public/stylesheets/components/alerts.less

@@ -65,6 +65,9 @@
 .alert-danger {
   .alert-variant(@alert-danger-bg; @alert-danger-border; @alert-danger-text);
 }
+.alert-alt {
+  .alert-variant(@alert-alt-bg; @alert-alt-border; @alert-alt-text);
+}
 
 .alert when (@is-overleaf = true) {
   a {

services/web/public/stylesheets/core/_common-variables.less

@@ -586,6 +586,10 @@
 @alert-danger-text:           @state-danger-text;
 @alert-danger-border:         @state-danger-border;
 
+@alert-alt-bg:               @state-info-bg;
+@alert-alt-text:             @state-info-text;
+@alert-alt-border:           @state-info-border;
+
 
 //== Progress bars
 //

services/web/public/stylesheets/core/ol-variables.less

@@ -108,6 +108,10 @@
 @alert-danger-text   : #FFF;
 @alert-danger-border : transparent;
 
+@alert-alt-bg    : @ol-blue-gray-1;
+@alert-alt-text  : @ol-type-color;
+@alert-alt-border: transparent;
+
 
 // Tags
 @tag-border-radius       : 9999px;