What Css Works In Thunderbird

As a developer who frequently works with Thunderbird, I understand the frustration of trying to make CSS work within this popular email client. Thunderbird has its own set of quirks when it comes to rendering HTML and CSS, and it often requires a different approach compared to standard web browsers. In this article, I’ll delve into the specific CSS properties and techniques that work well in Thunderbird, based on my personal experience and experimentation.

CSS Support in Thunderbird

Thunderbird, being an email client, has limited support for modern CSS properties and features. While basic styles such as font properties, color, and background can be applied effectively, more complex properties like flexbox, grid layout, and even some pseudo elements may not render as expected. It’s essential to keep this in mind when designing and coding email templates for Thunderbird.

Supported CSS Properties

Thunderbird offers relatively good support for basic CSS properties such as font, color, background, margin, padding, and border. However, it’s important to test these styles extensively to ensure consistent rendering across different email clients.

Unsupported CSS Properties

Properties like display: flex and display: grid are not fully supported in Thunderbird. Additionally, pseudo elements such as ::before and ::after may not work as expected. It’s crucial to find alternative approaches or fallbacks for these unsupported properties to maintain a cohesive design in Thunderbird.

Workarounds and Best Practices

In order to ensure a consistent and visually appealing email layout across different clients, including Thunderbird, it’s essential to follow certain best practices and utilize specific techniques. Inline styles, table-based layouts, and explicit width and height declarations can often help achieve more predictable rendering in Thunderbird.

Inline Styles

While modern web development encourages external CSS files, for email templates, it’s often necessary to rely on inline styles. Thunderbird tends to render inline styles more reliably than external stylesheets, so it’s a common practice to inline as much CSS as possible within the HTML elements.

Table-Based Layouts

In complex email designs where achieving consistent layouts across email clients is crucial, using table-based layouts can be an effective approach. Nesting tables and using inline styles within table elements can provide the necessary structure and support for Thunderbird.

Explicit Width and Height

Explicitly defining the width and height of elements can help prevent unexpected rendering issues in Thunderbird. By specifying exact dimensions, it’s possible to minimize the impact of any rendering inconsistencies that may arise within the email client.

Personal Advice

Based on my experience, designing for email clients like Thunderbird requires a healthy dose of patience and thorough testing. It’s important to create a consistent fallback strategy for CSS properties that may not be fully supported. Additionally, staying updated with the latest best practices and techniques for email development is crucial to overcoming the challenges posed by Thunderbird’s CSS limitations.


While Thunderbird may present certain challenges when it comes to CSS support, with careful planning and adherence to best practices, it’s possible to create visually appealing and functional email templates that render well across different clients, including Thunderbird. By understanding its limitations and working within them, developers can ensure that their email designs provide a seamless experience for recipients using this popular email client.