diff --git a/src/calibre/gui2/tweak_book/editor/text.py b/src/calibre/gui2/tweak_book/editor/text.py
index 650520e2a9..ae33506339 100644
--- a/src/calibre/gui2/tweak_book/editor/text.py
+++ b/src/calibre/gui2/tweak_book/editor/text.py
@@ -240,6 +240,9 @@ class TextEdit(PlainTextEdit):
         pal.setColor(QPalette.ColorRole.Highlight, theme_color(theme, 'Visual', 'bg'))
         pal.setColor(QPalette.ColorRole.HighlightedText, theme_color(theme, 'Visual', 'fg'))
         self.setPalette(pal)
+        vpal = self.viewport().palette()
+        vpal.setColor(QPalette.ColorRole.Base, pal.color(QPalette.ColorRole.Base))
+        self.viewport().setPalette(vpal)
         self.tooltip_palette = pal = QPalette()
         pal.setColor(QPalette.ColorRole.ToolTipBase, theme_color(theme, 'Tooltip', 'bg'))
         pal.setColor(QPalette.ColorRole.ToolTipText, theme_color(theme, 'Tooltip', 'fg'))