I am following below article to create a custom master page, but got stuck.
I have saved html and css file from github as per the below link, however after saving as .css and .html, and importing in desinger respective master page is not showing and which lead to no option found when I go to desinger manager to publish custom master page. Please help where I was doing wrong? Thank you.
https://www.c-sharpcorner.com/article/create-a-custom-master-page-in-html-for-Sharepoint-online/ 









