Custom CSS

Learn how to use Letterhead's Custom CSS feature to control the look and feel of your newsletter.

What is Custom CSS in Letterhead?

Custom CSS  (Cascading Style Sheets) is an advanced feature of Letterhead inside the sending email settings of your account.

Emails are essentially little web pages that appear in your inbox at their core. When creating a newsletter with Letterhead, we take your content and format it into HTML, which gets sent out via email. CSS lets you style the look and feel of the HTML that gets created.

What can it do? 

Using Custom CSS can help you modify the look and feel of your newsletter to better match your existing brand or design expectations. You can take the entire style sheet of your current website and insert it, though you should be prepared to make modifications, or you can insert individual element styles to make more minor adjustments. 

What can't it do? 

Most importantly, not all CSS elements will render equally for all of your subscribers. Using our resources below, you should review the limitations of what CSS elements can work in various browsers, devices, and email clients.

Custom CSS will not help you change the structure or architecture of your newsletter. For example, you don't be able to embed custom HTML widgets or completely change the basic layout of your newsletter.

Additionally, the custom CSS feature doesn't flag typos or syntax errors in your code, so you'll want to ensure that what you insert is accurate. 


Recommended Resources 

  • CanIUseEmail -- Check what CSS elements are compatible with readers' email clients and version history.
  • Can I Email -- Another valuable resource for checking email which shows which versions of an email client support different CSS customizations. 
  • Using CSS In Email: The Real History -- A brief overview of HTML emails and CSS within them by Chris Coyier of CSS-Tricks