Hi ​@Rosie.Clément, welcome to the community!

So the right answer depends on which Outlook version and on which platforms (Yes, it all matters!).  My best suggesting is to use an inbox testing tool so you can preview and iterate.  The two that I have used are:

• Litmus Email Testing
• Email on Acid

There may be others, but these tools let you see what your email looks like on dozens (hundreds?) of different email clients and on different platforms.  For example, Outlook on Windows Desktop can be different than Outlook on IOS, and different on Outlook 365 (on the web).

However, to cut to the chase, I find using “Tables” the best method to control most look and feel as it gives you the most control over more settings to test and tweak.  There are situation that you may require you do it manually in HTML so that you can add additional Outlook specific coding to make it work (e.g. inline styles) - so you may consider going back to your HTML method to fine tune this for Outlook.  

Good luck, and let us know how it goes!

Hello ​@retention!

Thank you so much for your quick answer and for your tips! 

I’ll test the three types of 50/50 design with the two tools you suggested and will let you know how it went. 

Have an amazing rest of your day!