diff --git a/index.html b/index.html
index 6f694c4..f045630 100644
--- a/index.html
+++ b/index.html
@@ -12,6 +12,7 @@
div.column{display: inline-block; vertical-align: top; width: 50%;}
div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
ul.task-list{list-style: none;}
+ .display.math{display: block; text-align: center; margin: 0.5rem auto;}