Inconsistent formatting between eM Client and Gmail

Hi all! I’m new to eM Client and really like it, except I’m noticing that the text and paragraph formatting shown in the client is different than in Gmail. This comes in line spacing, font size, etc. If I draft in eM Client, but then look at it in Gmail (web), I have to add spaces, etc. Now I have started going into the email in Gmail, deleting the formatting, and picking Sans Serif and normal size text, but that is a lot of work to make sure the formatting looks normal.

Even worse though is that content that may have been copy/pasted looks consistent on my end, but when I send, it looks different. It looks totally embarrassing.

What can I do?

Here’s an example.

This is how it looks in my outbox:

This is what they received (how it looks when they replied):

I think maybe Gmail is changing the formatting when you edit it in the web interface. If you just send it from eM Client, without editing it in the Gmail web interface, how does it look?