Design issues in generated invoice.

steps to reproduce:

1) Log in as admin -> create one prepaid customer

2) Refill some amount to customer account -> login as customer

3) Go to billing ->invoices -> Download the generated invoice and check mention point

4) we need credit of month ,Product & service  , total call amount , subtotal in bold like invoice date.

5)  we need bill no and country name in one line like Bill to : checkingamount India.

6)  we need  date, description , amount box bold like invoice number box.

Actual result :Generated invoice have design issue.
Expected result :Generated invoice display proper title and box.