Do not add HTML mixin if not building html

src/pydata_sphinx_theme/translator.py

@@ -83,6 +83,11 @@ def setup_translators(app: Sphinx):
     behavior and configuration, and _only_ add the extra bootstrap rules.
     If we don't detect an HTML-based translator, then we do nothing.
     """
+
+    # Do not add the mixin if the builder format is not HTML:
+    if app.builder.format != "html":
+        return
+
     if not app.registry.translators.items():
         try:
             default_translator_class = app.builder.default_translator_class
@@ -101,10 +106,6 @@ def setup_translators(app: Sphinx):
         app.set_translator(app.builder.name, translator, override=True)
     else:
         for name, klass in app.registry.translators.items():
-            if app.builder.format != "html":
-                # Skip translators that are not HTML
-                continue
-
             translator = types.new_class(
                 "BootstrapHTML5Translator",
                 (