JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script>
    <body>
        <div id="main_area">
            <div id="text">
            <p>
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            </p>
            <p>
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            </p>
            <p>
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            </p>
            <p>
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CSS

@media print {
        /* prevents the element from being printed in the pdf */
       .no_print, .no_print * {
            display: none !important
        }
    }
    #main_area {
        padding: 2px;
        width: 100%;
        background: #fff;
        color: #333;
    }
    #page_break {
        position: absolute;
        top: 0;
        width: 100%;
        opacity: 0.2;
    }
    #page_break > div {
        width: 100%;
        height: 5cm;
        border-bottom: 5px solid red;
        margin-bottom: -5px;
    }

JavaScript

var pixelsPerInch = 96;
var cmPerInch = 2.54;
var pixelsPerCm = pixelsPerInch / cmPerInch;

var textHeight = $('#text').height();
var divisions = Math.floor((textHeight / pixelsPerCm) / 5);

var breaks = $('#page_break');
for (var i = 0; i < divisions; ++i) {
    $('<div>').appendTo(breaks);
}