HtmlSaveOptions.export_cid_urls_for_mhtml_resources property. Specifies whether to use CID (Content-ID) URLs to reference resources (images, fonts, CSS) included in MHTML documents...'<link href=3D"cid:styles.css" type=3D"text/css" rel=3D"stylesheet"...'<img src=3D"cid:image.003.jpeg" width=3D"350" height=3D"180" alt=3D""...