diff --git a/docs/build-hooks.mmd b/docs/build-hooks.mmd
index f86760ed215..484a98c9187 100644
--- a/docs/build-hooks.mmd
+++ b/docs/build-hooks.mmd
@@ -1,4 +1,5 @@
 flowchart TB
+    classDef default fill:transparent, color:#000;
     classDef hook-parallel fill:#ffb3b3,stroke:#000;
     classDef hook-sequential fill:#ffd2b3,stroke:#000;
     classDef hook-first fill:#fff2b3,stroke:#000;
diff --git a/docs/output-generation-hooks.mmd b/docs/output-generation-hooks.mmd
index e356412cbc1..eccecdc9550 100644
--- a/docs/output-generation-hooks.mmd
+++ b/docs/output-generation-hooks.mmd
@@ -1,5 +1,5 @@
 flowchart TB
-    classDef default fill:#fff;
+    classDef default fill:transparent, color:#000;
     classDef hook-parallel fill:#ffb3b3,stroke:#000;
     classDef hook-sequential fill:#ffd2b3,stroke:#000;
     classDef hook-first fill:#fff2b3,stroke:#000;