panopoly-widgets.css shouldn't mess with ALL tables, just Table widgets

panopoly-widgets.css includes the following code:

/* Table Widget - Responsive */
@media only screen and (max-width: 480px) {
  table.tablefield {
    display: none;
  }

  table.mobile-table {
    display: block;
  }

  table {
    margin: 50px;
  }

  td, th {
    padding: 10px;
    text-align: left;
  }
   // etc...
}

As you can see, it includes some styles that apply to ALL tables. It's also a little strange, in that it's hiding the normal table, and replacing it with table.mobile-table but applying styles to all tables (whereas it could just get away with applying to table.mobile-table for doing Table widgets). So, I suspect that was left over from a previous approach at implementing this functionality.

This code originally comes from #1774072: Make Table Widget Responsive which states that the original intent is just to affect Table widgets.

I propose we only apply those styles to table.mobile-table.