I am using blink html converter to save an HTML source as PDF file.
Even thoug I set all margins to zero, the created PDF keeps an offset on top and left margin

while works fine for right and bottom margin:

For top margin I get the desired result if I set a negative margin, but if I try doing the same for left margin the program crashes with error could not find valid signature (%pdf-).
In documentation I didn't find any properties to set to avoid this offset.