Add a follow call to action to the bottom of the latest tweets widget for WordPress

latest-tweets-follow-button.php

<?php
add_filter( 'latest_tweets_render_after', 'prefix_add_follow_button', 10, 0 );
/**
 * Add a follow link to the bottom of the latest tweets widget.
 *
 * @author FAT Media, LLC
 * @link   http://wpbacon.com/tutorials/latest-tweets-follow-button/
 *
 * @todo   Change 'prefix' to your theme or plugin prefix.
 * @todo   Change 'text-domain' to your theme or plugin text domain.
 */
function prefix_add_follow_button() {
	// Your Twitter handle.
	$handle = 'yourhandle';

	// Text you'd like to use for your button.
	$follow_text = __( 'Follow Us On Twitter', 'text-domain' );

	// HTML Markup for your button.
	$content = '<footer>';
		$content .= '<p><a target="_blank" href="https://twitter.com/' . $handle .'">' . $follow_text . '</a></p>';
	$content .= '</footer>';

	return $content;
}

latest-tweets-style.css

/* Latest Tweets Widget
--------------------------------------------- */

.sidebar .widget.widget_latest_tweets_widget {
	padding: 40px 0 0;
	padding: 4rem 0 0;
}

.sidebar .widget_latest_tweets_widget .widgettitle {
	padding: 0 40px;
	padding: 0 4rem;
	margin: 0;
}

.latest-tweets ul li {
	border-bottom: 1px solid #E1E1E1;
	padding: 20px 40px;
	padding: 2rem 4rem;
}

.latest-tweets .tweet-text {
	margin: 0 0 5px;
	margin: 0 0 .5rem;
}

.latest-tweets .tweet-details time {
	color: #707070;
}

.latest-tweets footer {
	padding: 20px 40px;
	padding: 2rem 4rem;
}

.latest-tweets footer a {
	background: #2CA1FF;
	border-radius: 4px;
	color: #fff;
	display: block;
	font-size: 16px;
	font-size: 1.6rem;
	margin: 0;
	padding: 10px;
	padding: 1rem;
	text-align: center;
}

.latest-tweets footer a:hover {
	background: #59B5FF;
}