<style>
    .modal-window {
        display: none;
        position: absolute;
        z-index: 100;
        background: #eee;
        padding: 5px;
        border-radius: 5px;
        box-shadow: 2px 2px 5px #000000;

        left: 30%;
        top: 30px;
    }
    .modal-window-close {
        position: absolute;
        font-size: 10px;
        cursor: pointer;
        right: 4px;
        top: 4px;
    }
    .modal-window-title {
        text-align: center;
    }
    .modal-window-content {
        padding: 5px;
    }
</style>
<script type="text/javascript">
    function showModal(self) {
        var modal = document.getElementById('modalWindow');
        var iframe = modal.getElementsByTagName('iframe')[0];
        iframe.src = self.href;
        modal.style.display = 'block';
        return false;
    }
</script>
<div id="modalWindow" class="modal-window">
    <div class="modal-window-close" onclick="this.parentNode.style.display='none';">Закрыть</div>
    <div class="modal-window-title">Я модальное окно)</div>
    <div class="modal-window-content">
        <iframe src="about:blank" frameborder="0"></iframe>
    </div>
</div>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aliquam facilisis lorem ac dapibus ullamcorper. Pellentesque vestibulum felis eu odio bibendum, <a href="http://javascript.ru" onclick="return showModal(this);">ткни сюда</a>, ut viverra leo vestibulum. Sed a ipsum posuere, egestas mauris vel, porta magna. Mauris malesuada ipsum in lectus auctor, vel venenatis turpis facilisis. Mauris at eros libero. Curabitur eleifend lorem vel feugiat dignissim. Nam non molestie tortor.</p>
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.modal-window-content {
        padding: 5px;
		width:75%;
		height:75%;
    }