All script and iframe tags must be entered on the theme of a page. The HTML Source Editor found within the content editor only accepts basic HTML tags, the type that would be accepted by an email service provider. All other code must be placed within the page's theme.

Our theme documentation describes how NationBuilder utilizes the Liquid language and SCSS to provide robust flexibility in page development.

One caveat is that we don't recommend customizing donation pages, as malformed code can break these pages. This is because they have extra security to scramble the information entered. This is indicated by the "s" in "https" at the beginning of the URL. It is also why donation and login pages reside at https://yournation.nationbuilder.com, rather than on your custom domain.