How to add Facebook, Google+ and Twitter sharing buttons without using a plugin in Genesis

functions.php

//* Add Facebook, Google+ and Twitter sharing buttons after header

add_action( 'get_header', 'facebook_share_btn_sdk' );
function facebook_share_btn_sdk() {
	echo '<div id="fb-root"></div>
			<script>(function(d, s, id) {
			  var js, fjs = d.getElementsByTagName(s)[0];
			  if (d.getElementById(id)) return;
			  js = d.createElement(s); js.id = id;
			  js.src = "//connect.facebook.net/en_US/sdk.js#xfbml=1&appId=357648750922513&version=v2.0";
			  fjs.parentNode.insertBefore(js, fjs);
			}(document, \'script\', \'facebook-jssdk\'));</script>';
}

add_action( 'wp_footer', 'google_share_init' );
function google_share_init() {
	echo '<script src="https://apis.google.com/js/platform.js" async defer></script>';
}

add_action( 'genesis_after_header', 'facebook_share_btn' );
function facebook_share_btn() {
	echo '<div class="social-media-sharing"><div class="wrap">
			<div class="fb-share-button social-share-btn" data-layout="button_count"></div>

			<div class="social-share-btn"><div class="g-plus" data-action="share" data-annotation="bubble"></div></div>

			<div class="social-share-btn"><a href="https://twitter.com/share" class="twitter-share-button" data-via="srikat">Tweet</a>
				<script>!function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0],p=/^http:/.test(d.location)?\'http\':\'https\';if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src=p+\'://platform.twitter.com/widgets.js\';fjs.parentNode.insertBefore(js,fjs);}}(document, \'script\', \'twitter-wjs\');</script>
			</div>
		</div></div>';
}

style.css

/* Facebook, Google+ and Twitter sharing buttons
--------------------------------------------------- */

.social-media-sharing {
	margin-top: 40px;
}

.social-share-btn {
	margin-right: 20px;
	display: inline-block;
	float: left;
}

.social-share-btn:last-child {
	margin-right: 0;
}