Did you open a support ticket or send us an email at support[at]beefree[io]? Because we haven't received your email.
This isn't a rendering issue but rather a design choice.
You first need to set the body width of your email message in the BEE editor. This setting is found under the Body tab in the top right menu in the General options section. Once you set the general width to say 500px, all your sections will have the same width.
In terms of layout & design, your email can stretch to the full width or have a boxed appearance. These two designs can be achieved with the background colors setting. You need to set the row background and content background of your structures with two different colors. For example, have a grey row background color (i.e. the outside of your email message) and have a white content background color. By doing this you'll see a boxed design :)
Hope this helps!