diff --git a/bin/em/variabletime/web/js/utils.js b/bin/em/variabletime/web/js/utils.js
index 473bd37..de2bef2 100644
--- a/bin/em/variabletime/web/js/utils.js
+++ b/bin/em/variabletime/web/js/utils.js
@@ -421,6 +421,7 @@ const sequencialPromises = async (iterable, callback = false) => {
 const toCssClass = (text, prefix = '') => {
     return prefix + 'vt_' + text
         .replaceAll('.','-dot-')
+        .replaceAll(' ','_')
         .replaceAll('#','-hash-')
     ;
 };