Update attribution.css

Author: nerdyJuffie

book/_static/attribution.css

@@ -2,3 +2,9 @@
 div.attribution > .admonition-title::after {
     content: "\f10d";
 }
+
+/* Hiermee worden alle afbeeldingen in de content 50% breed */
+img {
+    width: 50%;
+    height: auto;
+}