[REF] utm: review and simplify scss

Part of the overall v16 SCSS optimization/restyle, task-2704984

task-2892062

Part-of: odoo/odoo#96195

addons/utm/static/src/scss/utm_views.scss

@@ -1,27 +1,14 @@
-.o_utm_kanban {
-    .o_kanban_group {
-        padding: 0 ($grid-gutter-width * .25) $grid-gutter-width;
-
-        &:not(.o_column_folded) {
-            width: 380px;
-		}
-	}
+.o_kanban_renderer.o_utm_kanban {
+    --KanbanRecord-width: #{380px - 2 * ($grid-gutter-width * .25)};
+    --KanbanGroup-padding-h: #{$grid-gutter-width * .25};
+    --KanbanGroup-padding-bottom: #{$grid-gutter-width};
 
     #o_utm_actions {
-        margin: 0 ($o-kanban-dashboard-hpadding * -.5);
+        margin: 0 calc(var(--KanbanRecord-padding-h) * -1);
 
         > a {
-            border-color: rgba($border-color, .5);
-            padding: ($o-kanban-dashboard-hpadding * .25) ($o-kanban-dashboard-hpadding * .5);
+            padding: var(--KanbanRecord-gap-inner-v) var(--KanbanRecord-padding-h);
             white-space: nowrap;
         }
-
-        > :first-child {
-            border-left: 0;
-        }
-
-        > :last-child {
-            border-right: 0;
-        }
     }
 }

addons/utm/views/utm_campaign_views.xml

@@ -107,7 +107,7 @@
                                 </div>
                                 <div class="o_kanban_record_body">
                                     <field name="tag_ids" widget="many2many_tags" options="{'color_field': 'color'}"/>
-                                    <ul id="o_utm_actions" class="list-group list-group-horizontal"/>
+                                    <ul id="o_utm_actions" class="list-group list-group-horizontal my-0"/>
                                 </div>
                                 <div class="o_kanban_record_bottom h5 mt-2 mb-0">
                                     <div id="utm_statistics" class="d-flex flex-grow-1 text-600 mt-1"/>