diff --git a/sao/src/sao.less b/sao/src/sao.less
index 2a3a6042b6..df76158da7 100644
--- a/sao/src/sao.less
+++ b/sao/src/sao.less
@@ -578,7 +578,7 @@ img.icon {
     width: 100%;
 }
 
-@media screen and (max-width: @screen-sm-max) {
+@media screen and (max-width: @screen-xs-max) {
     .attachment-preview:not(:empty) {
         border-width: 0 0 1px 0;
         margin-bottom: 5px;