It seems that your recordset on the makes page may not have the value for the type. You can use the get variable for the type like this:
Styles.php?ItemMakeID=<?php echo(rawurlencode($row_rsMakes['ItemMakeID'])); ?>&ItemTypeID=<?php echo(rawurlencode($_GET['ItemTypeID'])); ?>
As for the recordset on your styles page I think it is mostly correct but you should be comparing the makeID column to your colname variable rather than the style column. If you just update the part in the where clause that is looking for:
WHERE ItemStyleID = colname
To be like this:
WHERE ItemMakeID = colname
I'm not sure if this is correct for the recordset but you will need to match up the column you are filtering on with the variable that holds this value. You could do it the other way around like you mentioned and keep the column name in the where the same but use your other get query parameter.
There should only be the two variables on the style page recordset for filtering. One for the make, and another for the type. You are correct about the where clause in your last sentence.
