dropdown not aligned with label in zendesk form

Hi, I have challenge to update my request custom field (multi-select) to allow left alignment.

i have adjust in style.css the width as below :

#request_custom_fields_28159647845273{
  width: 500px
}

But when hover to the multi selection, the width is way too ugly and it is on the right alignment. 

I have very least knowledge in style.css or script.js

anyone can help me ?