Hello @sm1820,

Thanks for sharing your question with the Klaviyo Community!

The standard recommended email width is 600px as you have set. Emails rendering differently on Outlook clients is an industry wide issue as detailed in the My Email Looks Different When Viewed in Microsoft Outlook Help Center Article. Essentially, Outlook uses Microsoft Word to render HTML/CSS which may cause your emails to appear slightly off. 

I would also suggest taking a look at the actual image sizes you are placing side by side to ensure that the images you are using are of the same dimensions in width and height. If one of the images has a larger height than the image next to it, when Klaviyo automatically optimizes these images when placed next to each other to fit into the 300px column, the image may get shrunken. I’ve touched upon this subject in a similar Community post which I’ve included below for your review:

In addition, I would also suggest taking a look at the Optimal Email Template Width and How to Use Images in Emails Help Center Articles as other resources to learn more about images best practices within Klaviyo. 

I hope this helps!

David