Outlook Email Broken Layout Fix: Resolve CSS Flexbox Collapse for WCAG Accessibility Violations
Accessibility failures prevent screen readers from navigating templates, isolating disabled subscribers and increasing unsubscribe rates. Below is the targeted integration guide to fix CSS Flexbox Collapse inside Outlook 2019 templates when using MJML Framework.
Technical Breakdown
Outlook 2019 uses the Microsoft Word (MSO) which lacks support for standard rendering rules. This causes CSS Flexbox Collapse 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. Inject correct table roles (role='presentation') and keep color pairings above the WCAG AA contrast threshold of 4.5:1.
Remediation Code Block
To resolve this, modern layouts must be compiled down to Outlook-compliant nested HTML table models. Each flex container becomes a table row, and each flex child becomes a table data cell (td) with explicit pixel or percentage widths. 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="50%" valign="top" style="padding: 20px;">Column 1</td>
<td width="50%" valign="top" style="padding: 20px;">Column 2</td>
</tr>
</table>Live Code Sandbox Test
How to Deploy inside MJML Framework
Copy the fixed VML or table wrapper code block from the remediation box above.
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.