Fix .card-tabs .nav-tabs z-index colliding with dropdowns (#2752)

.changeset/fix-card-tabs-dropdown-zindex.md

@@ -0,0 +1,5 @@
+---
+"@tabler/core": patch
+---
+
+Fixed `.card-tabs .nav-tabs` sharing `z-index` with `.dropdown-menu`, which made dropdowns opened over card tabs render behind them.

core/scss/ui/_cards.scss

@@ -594,7 +594,7 @@ Card list group
 .card-tabs {
   .nav-tabs {
     position: relative;
-    z-index: $zindex-dropdown;
+    z-index: 1;
     border-bottom: 0;
 
     .nav-link {