diff --git a/assets/css/lesson.scss b/assets/css/lesson.scss
index 7c6de99..67b867e 100644
--- a/assets/css/lesson.scss
+++ b/assets/css/lesson.scss
@@ -104,6 +104,10 @@ code {
   background-color: inherit;
 }
 
+img {
+  max-width: 100%;
+}
+
 //----------------------------------------
 // Miscellaneous.
 //----------------------------------------