diff --git a/book/content/modelling/02_fluids/01_fluids.md b/book/content/modelling/02_fluids/01_fluids.md
index 0e50004f..e64cfca6 100644
--- a/book/content/modelling/02_fluids/01_fluids.md
+++ b/book/content/modelling/02_fluids/01_fluids.md
@@ -120,7 +120,7 @@ Flows of fluids (liquids and gases) follow the same principal characteristics. I
 
 :::{figure-md} fig-fluid-vortex-island
 
-<img src="https://upload.wikimedia.org/wikipedia/commons/2/2c/Vortex-street-1.jpg" width="40%" class="rotate90">
+<img src="https://upload.wikimedia.org/wikipedia/commons/2/2c/Vortex-street-1.jpg" width="40%" class="rotate-90">
 
 Von Kármán vortex street observed in nature. Soruce: [Wikkimedia Commons](https://commons.wikimedia.org/wiki/File:Vortex-street-1.jpg).
 :::