PDF is the format to send by default. It locks your layout: what you see in the editor is exactly what the recruiter opens, whatever their computer, phone or printer.
Try a color:
A PDF that ATS can read
People often say "ATS can't read PDFs". That has been false for years — provided the PDF contains real text and not an image. Ours is generated from the same engine as the preview: every word stays selectable, so screening software can read it.
Preview and PDF, strictly identical
Many tools render the preview with one technology and the PDF with another: mismatches are inevitable. Here the PDF is produced by printing exactly the page you're looking at. No surprise on opening.