table border fixes

src/scss/ui/_tables.scss

@@ -12,11 +12,13 @@
       }
     }
   }
+
+  >:not(:first-child) {
+    border-top-width: $table-border-width;
+  }
 }
 
 .table-responsive {
-  margin-bottom: $spacer;
-
   .table {
     margin-bottom: 0;
   }