Force A5 Paper-size in Chrome's print settings CSS

You could uset paper-css library as it will help you easily define the paper size by paper-css lib load the css file

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/paper-css/0.3.0/paper.css">

then set the style in the <head> part

<style>@page { size: A5 }</style>

then set the body class to A5 like the following

<!-- Set "A5", "A4" or "A3" for class name -->
<!-- Set also "landscape" if you need -->
<body class="A5">

  <!-- Each sheet element should have the class "sheet" -->
  <!-- "padding-**mm" is optional: you can set 10, 15, 20 or 25 -->
  <section class="sheet padding-10mm">

    <!-- Write HTML just like a web page -->
    <article>This is an A5 document.</article>

  </section>

</body>

for more information follow the link below https://github.com/cognitom/paper-css