Commerce Invoice Entity Print Styling I am using Commerce Invoice and Entity Print to generate .pdf-files of invoices. In Entity Print settings, I set the paper size to A4 and selected TCPDF as printing engine.
Then, I customized commerce-invoice.html.twig to my needs, which works fine.
But I cannot get rid of the two black borders that seperate the document header and footer I think.

Would be nice if anyone could give me a hint where these come from. I alread also tried to override entity-print.html.twig and remove the styles from there. Also I unchecked the checkbox in the entity-print settings. 
But these borders still appear on every .pdf-generation.
Thank you very much in advance!
What I found out is:
Every available printing engine has it's own requirements for the HTML-structure of the generatred invoice.
TCPDF needs a header and footer-tag inside the document. If you dont provide this elements, TCPDF will render them empty, but will in fact attach an hr-tag after the empty header and before the empty footer.
I switched to DOMpdf as printing engine, which also offers the possibility to define a page header and footer, but ignores them when empty and doesn't render any additional HTLM by default.
pro: DOMpdf supports more CSS rules and makes it easier to style the invoice with CSS
con: DOMpdf takes some seconds to render/print the document from the HTML, while TCPDF is very fast.