This question is a solution sample. I'm not a very experienced programmer. The main question is: Did i forget something?

Sometimes it is neccessary to use higher report resolutions than 90DPI. I found many workarounds to avoid different representations on different resolutions. I think it would be the easiest way to provide report dependend stylesheets. I have tried:

• inherit from web.report_assets_common (Makes SCSS accessible for all reports)

• <style> and <script> tags in report template (Maybe I'm dumb but both simply don't work with wkhtml)

• inherit web.report_layout and add a dynamic style attribute to the html tag (No success)

then I've found a new mechanism in 13.0: update_scss().

This methon in base -> res_company.py updates an attachment named res.company.scss which will be used in reports to change company colors and font. So I inherit from res.company and wrote this:

class Company(models.Model):
   _inherit="res.company"

def update_scss(self): 
    super(Company, self).update_scss()        
    paperformat = self.paperformat_id 
    if paperformat.dpi:
        # get the scss file and decode it
        attachment = self.env['ir.attachment'].search([('name', '=', 'res.company.scss')])
        scss_data = base64.b64decode(attachment.datas).decode('utf-8')
        # update the string and overwrite the 
        scss_string = '{}\n html {{font-size: 12pt / 90 * {};}}'.format(scss_data, paperformat.dpi)
        scss_data = base64.b64encode((scss_string).encode('utf-8'))
        attachment.write({'datas': scss_data})
   return ''

I checked the appearance with several dpi values now they're nearly similar.

Do you know other solutions? By doing it this way, do you see any risks?