Trying to remove the 'margin-top:48px' on one page

I have tried entering page specific CSS to remove this
margin-top:48px
using

.td-post-template-8 .td-main-content {
margin-top: 0px;
}

It works fine in the debugger, tried refering to the post with
#post-346 .td-post-template-8 .td-main-content {
margin-top: 0px;
}

Still not working
(http://www.dalat.org/web/da-school-history/)
see (pic)

OK – through a process of trial and error it was

#post-346.td-post-template-8 .td-main-content, .td-post-template-8 .td-main-sidebar {
margin-top: 0px;
}