Customising mail layouts and templates

I am not sure how to customise the mail layout / template.
What ever I do, the content table is forced to a width of 570px.
I just want to make full width for instance.
Similarly, there is a padding of 35px on the inner cell, how can I update this value?
Any idea?

Hi @chris ,

Going there: {yourHost}/{yourAdminArea}/system/mailtemplates/index/layouts

Then clicking on the template you want to update, you should be able to update the HTML (and the CSS).

 <table class="inner-body" align="center" width="570" cellpadding="0" cellspacing="0">
        <!-- Body content -->
        <tr>
            <td class="content-cell">
                {{ content|raw }}
            </td>
        </tr>
    </table>