Defining units as pixels will work just fine (just not here because of the code that's being stripped by Marketo). Here's more info on this issue - along with the solution (https://www.emailonacid.com/blog/article/email-development/dpi_scaling_in_outlook_2007-2013/ ). I also describe the issue in great detail above.
It all boils down to these three basic principles in order to ensure responsive templates render in Outlook when the user's Windows scaling is set to 125% or 150%:
1) Use inline styles and px units on tables. (supported in Marketo)
2) Use this tag to make VML scale. (not supported in Marketo)
xmlns:v="urn:schemas-microsoft-com:vml"
xmlns:o="urn:schemas-microsoft-com:office:office"
3) Use MSO-xxx for cellspacing and cellpadding (supported in Marketo)
This issue has been discussed as much as it can, here on the community. Now, we all just need to wait for the Marketo engineers to dedicate the time needed to finally fix it.
.png)