How to add -Please Select- option under a select box variable on catalog item - Developer Community - Question - ServiceNow Community
How to hide Select box variable options. - Developer Community - Question - ServiceNow Community
GitHub - PhilippeMarcMeyer/vanillaSelectBox: A dropdown menu with lots of features that takes a select tag and transforms it into a single or multi- select menu with 1 or 2 levels
Design A Custom Select Box Using HTML, CSS & JavaScript - YouTube