Like all WYSIWIG editors, the High-Level WYSIWIG Email Editor has a few minor limitations and issues.
(including playing around with some background colors from time to time and not being able to Left-Align emails easily - more details here)
Luckily, if you come across a limitation where the editor is not doing what you'd like it do, there's a very easy fix.
Simply create your email in one of the awesome dedicated HTML Email Design tools and then paste the compliant HTML into Growably by using this option when you're creating your email:
(our favorite tool for when we do need to create fancy looking emails is Stripo - most people can get by on their free plan)
With all that said, we strongly recommend NOT using fancy looking HTML Email templates in your Marketing Emails.
We've sent many millions of marketing emails over the years and every single time we've run A/B testing, basic text only emails with no graphics / fancy design always win with better deliverability and results every single time.
(there's more details here on getting better email deliverability)