Fix CSS Grid Broken Columns in Mozilla Thunderbird — HubSpot Guide for Transactional & System Notifications
Transactional emails (receipts, password resets, shipping alerts) carry critical operational data. Spacing collapses or broken buttons can block users from completing essential user journeys. Below is the targeted integration guide to fix CSS Grid Broken Columns inside Mozilla Thunderbird templates when using HubSpot.
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.
HubSpot Behaviors
HubSpot's COS template manager automatically wraps content blocks in dynamic div structures to support their drag-and-drop system. These extra wrappers force styling inheritances that override inline td paddings, leading to spacing collapses in Outlook. Setting explicit table element attributes is crucial. Because system notifications are triggered frequently, ensure your CSS rules are completely inlined to guarantee readability in high-volume, automated delivery queues.
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 HubSpot 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
How to Deploy inside HubSpot
Copy the fixed VML or table wrapper code block from the remediation box above.
In HubSpot's Design Manager, edit the modules section. Create a 'Rich Text' or 'HTML' module block. Double-click the block, choose 'Tools' or 'Advanced', click 'Source Code', and drop the code snippet inside.