Владислав Черненко

.text{
    color: #fff;
    mix-blend-mode: difference;
}

document.addEventListener( 'wpcf7mailsent', function( event ) {
    //...
}, false );

max-height:calc(100vh - ваша_шапка_и_отступы);
overflow-y:auto;

<a href="#popup-id-1" class="popup-link">Open 1</a>
<a href="#popup-id-2" class="popup-link">Open 2</a>

<div id="popip-id-1" class="popup"></div>
<div id="popip-id-2" class="popup"></div>

$('.popup-link').click(function (e) {
  e.preventDefault();
  var $data = $(this).attr('href');
  $($data).fadeIn();
});

var link = $('.file').attr('href');

var file_ext = link, parts, ext = ( parts = file_ext.split("/").pop().split(".") ).length > 1 ? parts.pop() : "";

alert( ext );