diff --git a/book/external/Sphinx-Image-Inverter b/book/external/Sphinx-Image-Inverter
index c497add..6789ae2 160000
--- a/book/external/Sphinx-Image-Inverter
+++ b/book/external/Sphinx-Image-Inverter
@@ -1 +1 @@
-Subproject commit c497add7fea53bacdd24f1c7fa5ec7a850e5f9d0
+Subproject commit 6789ae2128e183874f758b05b897580aba587689
diff --git a/book/features/custom_colors.md b/book/features/custom_colors.md
index e004f9b..c5ddb7d 100644
--- a/book/features/custom_colors.md
+++ b/book/features/custom_colors.md
@@ -127,6 +127,7 @@ html[data-theme="dark"] {
 
 <div class="newcolor">HTML text</div>
 
+(filter)=
 ### Light and dark mode different colors using a color filter
 
 ::::{warning}