live demo

html

<div class="small-container">
        <p id="marquee_paragraph">This is a looooong text with marquee.</p>
</div>

javascript

var marqueeParagraph = document.getElementById('marquee_paragraph');
new Marquee(marqueeParagraph,{
    edgeDelay: 1000,
    style: 'back_and_forth' // back_and_forth or loop
});