Margins are applied to all pages. A cover page with no margins can be achieved by few ways:
Solution 1. The easiest way is to run 2 phases - convert HTML to PDF and afterwards join a cover page with the PDF.
// create the API clients
$html_to_pdf_client = new \Pdfcrowd\HtmlToPdfClient("your_username", "your_apikey");
$pdf_to_pdf_client = new \Pdfcrowd\PdfToPdfClient
// run the conversion for a cover page
$cover = $html_to_pdf_client->convertFile("conver.html");
// if it's always the same, you can create it just once and use a local file
// run the conversion for a content of document
$document = $html_to_pdf_client->convertFile("document.html");
// join cover page and document
Solution 2: Let's say that your final PDF has maximum 10 pages. Let your document HTML to have 1st page empty (e.g. with CSS page break rules). Create a cover page PDF with 1 cover page and 9 empty pages (e.g. with <div style='height: 7000'>). Use the PDF with setMultipageWatermark
Solution 3: Quite complicated solution is to update your HTML to define margins inside (e.g. with fixed positions or dummy HTML elements) and use $client->setNoMargins(true)
I'd prefer 1st solution because it's the most flexible and can combine any type of PDFs.
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