JSFiddle - React, Tailwind, and code Playground

HTML

<div id="page">
    <div id="bar-header">Header</div>
    <div id="content">
        <div class="content-section">
             <h2>Content 1</h2>
 <a name="section-1"></a>

        </div>
        <div class="content-section">
             <h2>Content 2</h2>
 <a name="section-2"></a>

        </div>
        <!-- -->
        <div class="content-section">
             <h2>Content 2</h2>
 <a name="section-2"></a>

        </div>
        <div class="content-section">
             <h2>Content 4</h2>
 <a name="section-2"></a>

        </div>
    </div>
    <div id="bar-footer">Footer</div>
</div>

CSS

/* added: */
 h2 {
    display: inline-block;
}
body {
    margin: 0;
    padding: 0;
    background: transparent;
    width: 1280px;
    height: 720px;
}
#content {
    /* added: */
    overflow: auto;
    /*position: fixed;
            top: 0px;
            left: 0px;*/
    width: 1280px;
    height: 720px;
    outline: 1px solid red;
}
ul {
    list-style-type: none;
    margin: 0px;
    padding: 0px;
}
#bar-header, #bar-footer {
    /*position: fixed;
            left: 0px;*/
    width: 1280px;
    height: 30px;
    background-color: darkgray;
}
#bar-header {
    top: 0px;
}
#bar-footer {
    top: 690px;
}
.content-section {
    background-color: lightgray;
    outline: 1px solid black;
    height: 300px;
}