diff --git a/attachment_preview/static/src/scss/attachment_preview.scss b/attachment_preview/static/src/scss/attachment_preview.scss
index 48318dee..9c2bf904 100644
--- a/attachment_preview/static/src/scss/attachment_preview.scss
+++ b/attachment_preview/static/src/scss/attachment_preview.scss
@@ -32,6 +32,7 @@
     height: 100%;
     float: right;
     position: relative;
+    z-index: 999;
 
     > .attachment_preview_iframe {
         width: 100%;