JSFiddle - React, Tailwind, and code Playground

HTML

<body>
		<main>
			<div class="simplemodal-container" style="position: fixed; left: 25px; top: 75px; z-index: 1002;">
				<div class="simplemodal-wrap">
					<div class="simplemodal-data">
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					</div>
				</div>
			</div>
		</main>
		<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
		<script>
			$(function() {
				var sc = $(".simplemodal-container");
				var outerWidth = sc.outerWidth(true);
				var outerHeight = sc.outerHeight(true);
				
				$("main").append("<div>outerWidth(true) x outerHeight(true):<br>" + outerWidth + " x " + outerHeight + "</div>");
				
				sc.css({ width: outerWidth, height: outerHeight });
			});
		</script>
	</body>

CSS

* { -moz-box-sizing: border-box; box-sizing: border-box; font-size: 16px; font-weight: normal; font-style: normal; font-family: sans-serif; }
ul { margin: 0 0 0.5rem; padding: 0 0 0 2rem; list-style: disc; }
p { margin: 0 0 0.5rem 0; padding: 0 }
.simplemodal-wrap { height: 100%; outline: 0; width: 100%; overflow: visible; }
.simplemodal-data { background-color: #ddd; padding: 1rem; }