Why does my flipbook have lines placed at the corners of each page?

Sometimes you can see small lines in the corners of your flipbook looking something like this:

​

If you see these lines, it means your PDF has crop marks indicating where the paper should be trimmed after printing. While crop marks are sometimes essential for document printing, there is obviously no use for them in online flipbooks. So how to remove them?

As you probably guessed, you can get rid of crop marks by simply cropping them out of your PDF. You can crop your PDF with Adobe Acrobat (use Adobe Acrobat Crop tool). You can also use free online tools like Sejda (crop with Sejda) or PDF Resizer (crop with PDF Resizer).

Next, you will need to replace the PDF in your flipbook with the cropped version. Without a doubt, this will give your flipbooks a way more elegant and professional look!