A SharePoint Online tutorial by Peter Kalmström
an earlier demo
Peter Kalmström, CEO and Systems Designer of kalmstrom.com
Business Solutions, showed how to add a link in the Content
Editor web part to a text file containing the CSS code in
the Site Assets library, instead of adding the CSS code
to the HTML source of the web part.
This "link to CSS" method is quicker to change, as you don't
have to open the page in edit mode and then open the source.
Instead you can make the change directly in the CSS file.
Content Editor web part, as described in the
you can enter the code in a .js or .htm file and save it
to the Site Assets. Then you can just add a link in the
Content Editor web part.
and upload it to the Site Assets library.
Add a Content Editor web part to the page.