/*Copy this to functions.php */
function add_top_bar_to_header() {
    ?>
    <div>
        <div id="top_bar_space"></div>
        <div id="top_bar_block">
            <a id="top_bar_button" target="_top" href="#">Add your Text Here</a>
        </div>
    </div>
    <?php
}
add_action('wp_head', 'add_top_bar_to_header');

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/*Copy this to customize or where you can add your CSS */

#top_bar_space {
    height: 0px;
}

#top_bar_block {
    z-index: 501;
    background-color: #000000;
    height: 55px;
    width: 100%;
    text-align: center;
    position: fixed;
    top: 0;
}

#top_bar_button {
    -webkit-appearance: none;
    background-color: #464646;
    border: 2px solid #fff;
    color: #fff;
    cursor: pointer;
    display: inline-block;
    line-height: 1;
    margin: 7px 0 0 0;
    padding: 8px 30px;
    font-family: inherit;
    text-align: center;
    text-decoration: none;
}

#top_bar_button:hover {
    background: red; 
	  color: #fff;
}