Add units to 0 values to enable correct max calculations

Without units, the CSS max function calculates a value of
0, which results in no right margin on dropdowns. This causes
the width on col-auto to overlap the value and the dropdown
caret.

This may be fixed in future tom-select, see PR:

orchidjs/tom-select#819

share/static/css/elevator/tom-select.bootstrap5.css

@@ -371,8 +371,8 @@
 }
 
 :root {
-  --ts-pr-clear-button: 0;
-  --ts-pr-caret: 0;
+  --ts-pr-clear-button: 0em;
+  --ts-pr-caret: 0em;
   --ts-pr-min: .75rem;
 }