Fix Max-Width Constraint Collapsing in iOS Mail (Apple) — Klaviyo 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 Max-Width Constraint Collapsing inside iOS Mail (Apple) templates when using Klaviyo.
Technical Breakdown
iOS Mail (Apple) uses the WebKit Mobile which lacks support for standard rendering rules. This causes Max-Width Constraint Collapsing elements to break or collapse when rendering templates.
Klaviyo Behaviors
Klaviyo's drag-and-drop template parser automatically wraps all user-defined block sections in proprietary 'kl-part' class selectors. When rendering templates inside Microsoft Word engines (Outlook 2007-2021), Klaviyo's nested flex fallback blocks can cause structural tables to collapse or shift columns. You must use explicit table widths to override Klaviyo's styling wraps. Inject correct table roles (role='presentation') and keep color pairings above the WCAG AA contrast threshold of 4.5:1.
Remediation Code Block
To secure design widths, always wrap your layout inside a parent table with a static, hardcoded HTML width attribute (e.g. width='600') targeting Microsoft clients using conditional comments. In your Klaviyo campaign manager, make sure you configure your links to run via {% unsubscribe %}.
<!--[if mso]>
<table role="presentation" align="center" border="0" cellpadding="0" cellspacing="0" width="600">
<tr>
<td>
<![endif]-->
<div style="max-width: 600px; margin: 0 auto;">
Centered Layout Content
</div>
<!--[if mso]>
</td>
</tr>
</table>
<![endif]-->Live Code Sandbox Test
How to Deploy inside Klaviyo
Copy the fixed VML or table wrapper code block from the remediation box above.
Open your Klaviyo template editor. Drag an 'HTML' block directly into your layout timeline (do not use a standard text box). Clear the default skeleton content inside the Klaviyo markup editor and paste the RenderOps corrected inline code.