diff --git a/emmental/nowplaying/autopause.py b/emmental/nowplaying/autopause.py
index d67004d..ae76463 100644
--- a/emmental/nowplaying/autopause.py
+++ b/emmental/nowplaying/autopause.py
@@ -25,6 +25,8 @@ class Entry(Gtk.Entry):
         self.connect("icon_release", self.__icon_release)
         self.connect("notify::value", self.__update_text)
 
+        self.add_css_class("card")
+
     def __set_value(self, newval: int) -> bool:
         if -1 <= newval <= 99:
             self.value = newval
diff --git a/tests/nowplaying/test_autopause.py b/tests/nowplaying/test_autopause.py
index 4621310..d3c4c0c 100644
--- a/tests/nowplaying/test_autopause.py
+++ b/tests/nowplaying/test_autopause.py
@@ -26,6 +26,7 @@ class TestAutopauseEntry(unittest.TestCase):
         self.assertIsInstance(self.entry, Gtk.Entry)
         self.assertTupleEqual(self.entry._timeout, (None, None))
         self.assertEqual(self.entry.get_max_width_chars(), 20)
+        self.assertTrue(self.entry.has_css_class("card"))
 
     def test_placeholder_text(self):
         """Test changing the placeholder text with the value."""