<style>
    #button {
        display: inline-block;
        background-color: #FF9800;
        width: 50px;
        height: 50px;
        text-align: center;
        border-radius: 50%;
        position: fixed;
        bottom: 25px;
        right: 25px;
        transition: background-color .3s,
            opacity .5s, visibility .5s;
        opacity: 0;
        visibility: hidden;
        z-index: 1000;

        & .bi {
            font-size: 2em;
            font-weight: bold;
            color: white;

        }
    }

    #button::after {
        content: "";
        font-family: FontAwesome;
        font-weight: normal;
        font-style: normal;
        font-size: 2em;
        line-height: 50px;
        color: #fff;
    }

    #button:hover {
        cursor: pointer;
        background-color: #333;
    }

    #button:active {
        background-color: #555;
    }

    #button.show {
        opacity: 1;
        visibility: visible;
    }

    /* Styles for the content section */

    .content {
        width: 77%;
        margin: 50px auto;
        font-family: 'Merriweather', serif;
        font-size: 17px;
        color: #6c767a;
        line-height: 1.9;
    }

    @media (min-width: 500px) {
        .content {
            width: 43%;
        }

        #button {
            margin: 30px;
        }
    }

    .content h1 {
        margin-bottom: -10px;
        color: #03a9f4;
        line-height: 1.5;
    }

    .content h3 {
        font-style: italic;
        color: #96a2a7;
    }
</style>
<a id="button"><i class="bi bi-arrow-up-short"></i></a>

<script src="https://code.jquery.com/jquery-3.7.1.min.js"
    integrity="sha256-/JqT3SQfawRcv/BIHPThkBvs0OEvtFFmqPF/lYI/Cxo=" crossorigin="anonymous"></script>
<script>
    let btn = $('#button');

    $(window).scroll(function () {
        if ($(window).scrollTop() > 300) {
            btn.addClass('show');
        } else {
            btn.removeClass('show');
        }
    });

    btn.on('click', function (e) {
        e.preventDefault();
        $('html, body').animate({ scrollTop: 0 }, '300');
    });

</script>