ConvertKit emails use HTML, so I can make them look like my site, right?
The truth is, most email clients don't support the modern HTML content you see on the web. With a web browser you can view animations, scripts, menus, etc. Emails, however, take a simpler approach.
Website HTML Vs. Email HTML
Email clients are far behind web browsers when it comes to their ability to display content. Web browsers can display a lot of interactive content and they're updated often.
Below is a quick guide of what things work and what doesn't when it comes to email.
Things you're safe to use
Static content like images and text.
Simple CSS to establish color, font size, line height, etc.
Fonts that are web safe.
Things to use with caution
These are some things not every email client supports and, as a result, may not be available to everyone:
Custom fonts - There are a lot of custom web fonts out there, but they need to be available for the person viewing them, and may not display for your subscribers.
Background images - If you include a background image in your custom template, it may display differently, or not at all, depending on the email client.
Things you shouldn't use
Some types of web content won't work at all in emails. It's important to avoid these because your recipients likely won't see them.
Important: You may see some of these things when previewing your email in the browser but it's highly recommended that you use the email preview for emails you're unsure of.
Embedded video and/or audio - Audio and video are both interactive and typically blocked by most email clients. Taking a screenshot of the video you'd like to include, and making it a link, is a great alternative.
iframe - An <iframe> element embeds one website into another and are often blocked by email clients. Taking a screenshot of the content you'd like to show, and making it a link, is a great alternative.
Javascript - A programming language that's common on the web for interactions, but is blocked by email clients.
Forms - Though forms are typically built with basic HTML, they need to send information through a programming language like Javascript, and won't be usable in an email.
Flash content - Flash is used for animations on some websites, but email clients block it. Adding a gif to your email is a great alternative!