fix(html): harden selector list splitting

Co-Authored-By: Virgil <virgil@lethean.io>

responsive.go

@@ -106,19 +106,29 @@ func splitSelectorList(selector string) []string {
 	parts := make([]string, 0, 1)
 	var b strings.Builder
 	var quote rune
+	escaped := false
 	depthParen := 0
 	depthBracket := 0
 	depthBrace := 0
 
 	for _, r := range selector {
+		if escaped {
+			b.WriteRune(r)
+			escaped = false
+			continue
+		}
+
+		if r == '\\' {
+			b.WriteRune(r)
+			escaped = true
+			continue
+		}
+
 		switch {
 		case quote != 0:
 			b.WriteRune(r)
 			if r == quote {
 				quote = 0
-			} else if r == '\\' {
-				// Keep escaped characters inside quoted strings intact.
-				continue
 			}
 		case r == '"' || r == '\'':
 			quote = r

responsive_test.go

@@ -243,3 +243,11 @@ func TestScopeVariant_PreservesNestedCommas(t *testing.T) {
 		t.Fatalf("ScopeVariant should preserve nested commas = %q, want %q", got, want)
 	}
 }
+
+func TestScopeVariant_PreservesEscapedSelectorCharacters(t *testing.T) {
+	got := ScopeVariant("desktop", `.nav\,primary, [data-state="open\,expanded"]`)
+	want := `[data-variant="desktop"] .nav\,primary, [data-variant="desktop"] [data-state="open\,expanded"]`
+	if got != want {
+		t.Fatalf("ScopeVariant should preserve escaped selector characters = %q, want %q", got, want)
+	}
+}