    def _update_footnote_area(self):
        """Update the page bottom size and our footnote area height."""
        if self.current_footnote_area.height != 'auto' and not self.in_column:
            self.page_bottom += self.current_footnote_area.margin_height()
        self.current_footnote_area.children = self.current_page_footnotes
        if self.current_footnote_area.children:
            footnote_area = build.create_anonymous_boxes(
                self.current_footnote_area.deepcopy())
            footnote_area = block_level_layout(
                self, footnote_area, -inf, None,
                self.current_footnote_area.page)[0]
            self.current_footnote_area.height = footnote_area.height
            if not self.in_column:
                self.page_bottom -= footnote_area.margin_height()
            last_child = footnote_area.children[-1]
            overflow = (
                last_child.position_y + last_child.margin_height() >
                footnote_area.position_y + footnote_area.margin_height() -
                footnote_area.margin_bottom)
            return overflow
        else:
            self.current_footnote_area.height = 0
            if not self.in_column:
                self.page_bottom -= self.current_footnote_area.margin_height()
            return False
Update the page bottom size and our footnote area height.
weasyprint/layout/__init__.py