noteweb: Rendering bird field notes for the Web

These rules style the rows in the index table. We want rules around the bottom, left, and right sides of the row.

tr.year-row
{   border-bottom: 1px solid black;
    border-left: 1px solid black;
    border-right:  1px solid black;
}

To help the reader's eye track across the table, we make every fifth row's bottom border thicker. The year-group class is added for rows whose years are evenly divisible by 5.

tr.year-group
{   border-bottom: 3px solid black;
}