[v4 css] inverted table styling

Created by: Mottie

When inverting a table style using the table-inverse class (demo):

1. Striping
   With a "table-striped" class, the stripes are not discernibly different. In the css, the definition is the same as for the non-inverted row styling:

   .table-striped tbody tr:nth-of-type(odd) {
     background-color: rgba(0, 0, 0, .05); /* $table-bg-accent; */
   }

2. Borders
   The border styling of the non-inverted tables is a very subtle, using a border color of #eceeef. On inverted tables, we see #fff! It's way to bright!

   .table-inverse td,
   .table-inverse th,
   .table-inverse thead th {
     border-color: #fff; /* $body-bg */
   }

3. Hover
   Hovering isn't as bad when no stripe is applied to the table; but when a stripe is applied, the hover is only slightly more discernible than the row color (demo)!

   .table-hover tbody tr:hover {
     background-color: rgba(0, 0, 0, .075) /* $table-bg-hover */
   }

This may not seem like a big deal to some of you young 'uns out there, but for elderly and visually impaired users, it would make a difference.