JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <iframe id="myframe" src="http://www.cnn.com/"></iframe>
</div>

CSS

.container {
    width: 100%;
    height: 250px;
    border: 3px solid blue;
}
.iframe-class {
    width: 100%;
    height: 100%;
    border: 3px solid red;
    overflow: auto;
}

JavaScript

$(function () {
    setIFrameSize();
    $(window).resize(function () {
        setIFrameSize();
    });
});

function setIFrameSize() {
    var parentDivWidth = $("#myframe").parent().width();
    var parentDivHeight = $("#myframe").parent().height();
    $("#myframe")[0].setAttribute("width", parentDivWidth);
    $("#myframe")[0].setAttribute("height", parentDivHeight);
}