diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
index 177557b371a6..5f40e7b0fb9a 100644
--- a/lib/matplotlib/colors.py
+++ b/lib/matplotlib/colors.py
@@ -960,6 +960,7 @@ def color_block(color):
                 '</div>'
                 '<div style="float: right;">'
                 f'over {color_block(self.get_over())}'
+                '</div>'
                 '</div>')
 
     def copy(self):