Fix variant offset calculation

Author: thecrypticace

packages/tailwindcss-language-service/src/util/getVariantsFromClassName.ts

@@ -60,11 +60,12 @@ export function getVariantsFromClassName(
   let offset = 0
   let variants = new Set<string>()
 
-  for (let part of parts) {
+  for (let [idx, part] of parts.entries()) {
     if (!isValidVariant(part)) break
 
     variants.add(part)
-    offset += part.length + state.separator!.length
+    offset += part.length
+    offset += idx < parts.length - 1 ? state.separator!.length : 0
   }
 
   return { variants: Array.from(variants), offset }