Custom Styling in email template

I have tried customise the email template to make it look a bit more like what I am looking for.

Not the core template, but from the wp-invoice settings page.

I have wrapped the elements in <div><p>… etc and initially added class’s to each and had the styling above <style>…</style>.

But the styles seemed to be ignored.

I then removed the classes and added style=”…”.

This worked a bit better as the styles were kept. my issue now is that backslashes are automatically added to cancel out the styles which I then need to delete before sending the email.

IE

<div style=”width:80%; margin-left:10%; background-color:white; padding:25px;”>….</div>

gets changed to

<div style=\”width:80%; margin-left:10%; background-color:white; padding:25px;\”>….</div>

so you can see that slashes are added at the start and the end – <div style=\”…\”>

Any help in rectifying this would be great.