diff --git a/src/css/custom.css b/src/css/custom.css
index e9e2e23b9ae8c25e77dc98d43b04c66f0dba8c4c..cd98ea406f8ba915bde7f72e18423c4a0746d7a6 100644
--- a/src/css/custom.css
+++ b/src/css/custom.css
@@ -111,6 +111,8 @@ input[type='number'] {
   line-height: 1.5;
   padding: 1rem;
   border-radius: 8px;
+  tab-size: 4;
+  -moz-tab-size: 4;
 }
 
 .footer {