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USE CASE Target

Fix CSS Grid Broken Columns in Mozilla Thunderbird — MJML Framework Guide for Editorial & Content Newsletters

Editorial newsletters rely on content layout readability and structural text spacing. If fonts default to Times New Roman or layout borders break, subscriber engagement metrics suffer. Below is the targeted integration guide to fix CSS Grid Broken Columns inside Mozilla Thunderbird templates when using MJML Framework.

Technical Breakdown

Mozilla Thunderbird uses the Gecko which lacks support for standard rendering rules. This causes CSS Grid Broken Columns elements to break or collapse when rendering templates.

MJML Framework Behaviors

The MJML transpilation compiler parses dynamic columns and wraps them in custom HTML conditional tags. If you paste direct tables or VML code blocks inside an MJML layout without proper escaping, the MJML compiler will try to clean the code, resulting in stripped Outlook namespaces and broken layouts. Keep your editorial body clean. Strip redundant CSS class definitions using Vaporize to ensure the newsletter stays under Gmail's 102KB clipping ceiling.

Remediation Code Block

Always compile grid layouts using standard percentage-width or pixel-width nested tables aligned with the align='left' attribute. This acts as a responsive grid block that floats and adapts naturally to any viewport size. In your MJML Framework campaign manager, make sure you configure your links to run via {{unsubscribe_link}}.

<table role="presentation" border="0" cellpadding="0" cellspacing="0" width="100%">
  <tr>
    <td width="48%" align="left" valign="top" style="padding-bottom:10px;">Col 1</td>
    <td width="4%"></td>
    <td width="48%" align="left" valign="top" style="padding-bottom:10px;">Col 2</td>
  </tr>
</table>

Live Code Sandbox Test

Interactive MJML Framework Custom Sandbox

Target Environment: Mozilla Thunderbird

How to Deploy inside MJML Framework

1

Copy the fixed VML or table wrapper code block from the remediation box above.

2

Wrap the entire RenderOps corrected table block inside an '<mj-raw>' tag block. This tells the MJML compiler to bypass parsing on this segment, exporting the exact conditional statements into the final HTML output.

Targeted Fixes by Use Case & Industry