(a) In General. The day of an act, event, or default after which a designated period begins to run is not included when computing a period prescribed or allowed by these rules, by court order, or by statute. The last day of the period is included, but if that day is a Saturday, Sunday, or legal holiday, the period extends to the end of the next day that is not a Saturday, Sunday, or legal holiday.
(b) Clerk's Office Closed or Inaccessible. If the act to be done is filing a document, and if the clerk's office where the document is to be filed is closed or inaccessible during regular hours on the last day for filing the document, the period for filing the document extends to the end of the next day when the clerk's office is open and accessible. The closing or inaccessibility of the clerk's office may be proved by a certificate of the clerk or counsel, by a party's affidavit, or by other satisfactory proof, and may be controverted in the same manner.