/*Adds a bottom tab */
function add_floating_button_itc() {
    ?>
    <style>
	.floating-button-tab {
		font-family: inherit !important;
		background: #bfe6f0;
		position: fixed;
		left: 20px;
		bottom: 20px;
		top: auto;
		margin: 0;
		padding: 8px 16px;
		text-align: center;
		font-size: 12px;
		font-weight: bold;
		display: block;
		z-index: 100000;
		color: #ffffff;
		border-width: 0px;
		text-decoration: none;
		writing-mode: horizontal-tb;
		transform: none;
		cursor: pointer;
		border-radius: 6px 6px 6px 6px;
		line-height: 1.3;
		letter-spacing: 0.5px;
		box-shadow: 2px 4px 10px rgba(0,0,0,0.25);
		transition: background-image 0.3s ease;
	}
		
        .floating-button-tab:hover {
            background: #379cd6;
            color: #ffffff;
        }
    </style>

   <a class="floating-button-tab" href="https://..." target="_blank" rel="noopener noreferrer">
    Your Text</a>
    <?php
}
add_action('wp_footer', 'add_floating_button_itc');