2. Now paste your code into the assigned section: Header, Body, or Footer:
Adding custom HTML and CSS to your landing page is done the same way, you just need to use the HTML/CSS tab from the Settings menu.
The custom codes will only execute in preview mode or on the published page (and not in the editor).
Also, every published page will be including the jQuery library if the jQuery syntax can be found on the page. However, note that the page loading time might be slightly increased in this case.