Hi Lucie - welcome to MR!
The easiest way to make sure it is on it's own page is to put it in its own html file. Each chapter should be in a separate file and you can just place the quote file before the chapter file.
Are you using ePub2 or ePub3?? There are different techniques for the different versions.
For ePub2, I borrow some
<table> properties without having to use a table. It works great on my devices but I can't guarantee all devices support <table>s, although, it would be a pretty poor device/app that didn't... What device/app are you targeting for your book?
In my case (ePub2) I surround whatever I want to be vertically centered with a double <div>. You can style the interior paragraphs however you like... ie. horizontally centered. You can see a better explanation on
W3Schools website. They are a pretty decent resource for coding specifics.
Code:
CSS:
/* Vertically centered on page */
div.v-ctr {height:100%; width:100%; display:table; position:fixed;
padding:0; margin:0; text-indent:0}
div.v-ctr div {display:table-cell; vertical-align:middle;
padding:0; margin:0}
HTML:
<body>
<div class="v-ctr">
<div>
<p>yadda yadda yadda</p>
</div>
</div>
</body>
You can actually use the same technique for ePub3, but there are some more elegant solutions using display:flex... be aware that many, especially older, devices won't support ePub3 coding.
Cheers!