JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div id="conversation">
        <div class="header">
            <h3>TĂ­tulo</h3>
        </div>
        <div class="content">
            <ul>
                <li>Primeira conversa</li>
                <li>Segunda conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                <li>Terceira conversa</li>
                
            </ul>
        </div>
    </div>
</div>

CSS

body, html{
    height: 150%
}

#conversation{
    width: 400px;
    border: 1px solid #eee;
    overflow: hidden;
}

.header {
    background: #4ECDC4;
    color: #fff;
    text-align: center;
    height: 40px;
}

.header h3 {
    margin: 0;
    padding: 0;
    line-height: 40px;
}

.content{
    overflow-x: hidden;
    height: 400px;
}

ul{
   margin: 0;
   padding: 0;
}

li{
    list-style: none;
    padding: 20px 10px;
    border-bottom: 1px solid #eee;
}