diff --git a/modoboa/static/css/offline.css b/modoboa/static/css/offline.css
index c0802bd07..17daf50a5 100644
--- a/modoboa/static/css/offline.css
+++ b/modoboa/static/css/offline.css
@@ -72,7 +72,7 @@ h2 {
 }
 
 .input-group input {
-    width: 100%;
+    width: calc(100% - 20px);
     padding: 10px;
     border: 1px solid #ddd;
     border-radius: 5px;