Fix Broken SVG Image Vectors in Mozilla Thunderbird — Klaviyo Guide for Client Rendering Engine Anomalies
Email client rendering variations are caused by differences in parser engines. Legacy Outlook engines ignore modern block models, forcing layouts to stack vertically. Below is the targeted integration guide to fix Broken SVG Image Vectors inside Mozilla Thunderbird templates when using Klaviyo.
Technical Breakdown
Mozilla Thunderbird uses the Gecko which lacks support for standard rendering rules. This causes Broken SVG Image Vectors 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. Test layout code regressions side-by-side using the Campaign Diff Comparator before pushing visual style changes to your production templates.
Remediation Code Block
Always convert logo assets and icons from vector SVG formats into web-friendly PNG or JPG formats. If vector rendering is required, host the SVG on a CDN with an absolute URL and define a PNG fallback utilizing conditional comments. In your Klaviyo campaign manager, make sure you configure your links to run via {% unsubscribe %}.
<!--[if mso]>
<img src="https://example.com/fallback-logo.png" width="120" height="40" alt="Logo" style="display:block;border:0;">
<![endif]-->
<!--[if !mso]><!-->
<img src="https://example.com/vector-logo.svg" width="120" height="40" alt="Logo" style="display:block;border:0;">
<!--<![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.