Are we talking about "dnd themes" or "old themes/templates"?
Best way would be to download bootstrap, create a new file in the filemanager or designmanager(in the theme folder), open your main.css where all @imports are and "import" the it as last element.
Or you can upload the bootstrap.css to your filemanager, open the Hub Settings and set the bootstrap.css in the website settings. (Don't forget to do this in the blog too)
Are we talking about "dnd themes" or "old themes/templates"?
Best way would be to download bootstrap, create a new file in the filemanager or designmanager(in the theme folder), open your main.css where all @imports are and "import" the it as last element.
Or you can upload the bootstrap.css to your filemanager, open the Hub Settings and set the bootstrap.css in the website settings. (Don't forget to do this in the blog too)