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        ul {
            list-style-type: none;
            margin: 0;
            padding: 0;
            width: 25%;
            background-color: #f1f1f1;
            position: fixed;
            height: 100%;
            /*overflow: auto;*/
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        /*li a {*/
            /*display: block;*/
            /*color: #000;*/
            /*padding: 8px 16px;*/
            /*text-decoration: none;*/
        /*}*/

        /*li a.active {*/
            /*background-color: #4CAF50;*/
            /*color: white;*/
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<div style="margin-left:25%;padding:1px 16px;height:1000px;">
    <h2>Fixed Full-height Side Nav</h2>
    <h3>Try to scroll this area, and see how the sidenav sticks to the page</h3>
    <p>Notice that this div element has a left margin of 25%. This is because the side navigation is set to 25% width. If you remove the margin, the sidenav will overlay/sit on top of this div.</p>
    <p>Also notice that we have set overflow:auto to sidenav. This will add a scrollbar when the sidenav is too long (for example if it has over 50 links inside of it).</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
    <p>Some text..</p>
</div>

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