Converting the attached file to HTML with GroupDocs.Viewer (22.3) produces an output with very thick lines:
image.png (320.8 KB)
Converting the same file to PDF with GroupDocs.Conversion (22.2) looks much better:
image.png (230.6 KB)
400_B-PH 4ème ÉTAGE_Coffrage_CB.zip (751.0 KB)
There was no special code used for conversion.
using (var viewer = new Viewer(documentPath))
{
var options = HtmlViewOptions.ForEmbeddedResources("output_viewer{0}.html");
viewer.View(options);
}