diff --git a/pattern_library/static/pattern_library/src/scss/components/_iframe.scss b/pattern_library/static/pattern_library/src/scss/components/_iframe.scss
index 07c7a581..47227106 100644
--- a/pattern_library/static/pattern_library/src/scss/components/_iframe.scss
+++ b/pattern_library/static/pattern_library/src/scss/components/_iframe.scss
@@ -1,4 +1,5 @@
 .iframe {
+    box-sizing: content-box;
     width: 100%;
     border: 1px solid $light-grey;
     margin: 20px 0;