diff --git a/src/static/css/pad.css b/src/static/css/pad.css
index f1e12d2ac..a62677008 100644
--- a/src/static/css/pad.css
+++ b/src/static/css/pad.css
@@ -16,6 +16,9 @@ html {
   line-height: 16px;
   color: #3e3e3e;
 }
+html, *, *:after, *:before {
+  box-sizing: border-box;
+}
 *, p {
   margin: 0;
   padding: 0;