Is this a correct way to use the tag?
An updated method (as far as I understand it) could be something like this:
Section Title
...
Section Title
...
main {
width: 100%;
...
...
}
#inner_wrapper {
max-width: 80%;
margin: 0 auto;
}
See: http://www.w3.org/TR/html-main-element/, http://www.sitepoint.com/html5-main-element/ or http://html5doctor.com/the-main-element/ for more info.