Add border-radius to table head

Created by: nikku

Coloring of thead overlaps the table border radius.

To fix it, add a border radius to the first and last td cell of the thead element in a table.

table thead tr:first-child td:first-child {
    .border-radius(4px 0 0 0);
}

table thead tr:first-child td:first-child {
    .border-radius(0 4px 0 0);
}

Or, fix border radius for tbody if that should be a bug.

table {
    tbody tr:first-child td:first-child {
        .border-radius(4px 0 0 0);
    }
    tbody tr:first-child td:last-child {
        .border-radius(0 4px 0 0);
    }
}