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ERROR TYPE Target

Fix CSS Flexbox Collapse in iOS Mail (Apple) — Campaign Monitor Guide 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 iOS Mail (Apple) templates when using Campaign Monitor.

Technical Breakdown

iOS Mail (Apple) uses the WebKit Mobile which lacks support for standard rendering rules. This causes CSS Flexbox Collapse elements to break or collapse when rendering templates.

Campaign Monitor Behaviors

Campaign Monitor wraps custom blocks in dynamic edit tags, which can break the column flow inside Outlook. Ensuring correct class names is essential. 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 Campaign Monitor campaign manager, make sure you configure your links to run via [unsubscribe].

<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

Interactive Campaign Monitor Custom Sandbox

Target Environment: iOS Mail (Apple)

How to Deploy inside Campaign Monitor

1

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

2

In Campaign Monitor, click the 'Source' button on your selected editable text region, or edit the template code files directly. Ensure you append the 'class="cs-editable"' flag if you need inline editing later.

Targeted Fixes by Use Case & Industry