Custom signup form for Jetpack subscriptions

jetpack-subscribe.php

<?php
/*
Plugin Name: Jetpack Subscribe
Description: Custom subscription UI for Jetpack
Version: 1.0
Author: Evan Solomon
Author URI: http://evansolomon.me/
*/

class ES_Jetpack_Subscribe {
	private static $instance;

	static function get_instance() {
		if ( ! self::$instance )
			self::$instance = new ES_Jetpack_Subscribe;

		return self::$instance;
	}

	private function __construct() {
		add_action( 'wp_enqueue_scripts',        array( $this, 'wp_enqueue_scripts' ) );
		add_action( 'cogitate_after_entry_meta', array( $this, 'render_form'        ) );
	}

	public function is_enabled() {
		// Only using the form on single pages
		return apply_filters( 'es_jetpack_subscribe_is_enabled', is_single() );
	}

	public function wp_enqueue_scripts() {
		if ( $this->is_enabled() )
			$this->enqueue_style();
	}

	public function enqueue_style() {
		wp_enqueue_style( __CLASS__, plugins_url( '/style.css', __FILE__ ) );
	}

	/**
	 * Mostly copied from jetpack/modules/subscriptions.php
	 */
	public function get_form() {
		// Presumably used by Jetpack server
		$referer = ( is_ssl() ? 'https' : 'http' ) . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
		$source  = 'jetpack_custom_subscribe';

		// Text fields
		$header            = apply_filters( 'es_jetpack_subscribe_form_header', "Want to get this magic in your inbox?" );
		$email_placeholder = apply_filters( 'es_jetpack_subscribe_form_email',  "Your electronic mail address" );
		$button            = apply_filters( 'es_jetpack_subscribe_form_button', "Please don't spam me" );

		$form = '<form action="" method="POST" accept-charset="utf-8" id="subscribe-blog">';
		if ( ! isset ( $_GET['subscribe'] ) )
			$form .= sprintf( '<p class="subscribe-title">%s</p>', esc_html( $header ) );

		$form .= sprintf( '<p>%s%s</p>',
			sprintf( '<input type="text" name="email" id="subscribe-field" placeholder="%s" />', esc_attr( $email_placeholder ) ),
			sprintf( '<input type="submit" value="%s" name="jetpack_subscriptions_widget" id="subscribe-submit" />', esc_attr( $button ) )
		);

		// Jetpack stuff
		$hidden  = '<input type="hidden" name="action" value="subscribe" />';
		$hidden .= sprintf( '<input type="hidden" name="source" value="%s" />', esc_url( $referer ) );
		$hidden .= sprintf( '<input type="hidden" name="sub-type" value="%s" />', esc_attr( $source ) );
		// Append to the form
		$form .= sprintf( '<p>%s</p>', $hidden );

		$form .= '</form>';

		return apply_filters( 'es_jetpack_subscribe_form', "<div class='jetpack-subscribe-form'>{$form}</div>" );
	}

	public function render_form() {
		if ( $this->is_enabled() )
			echo $this->get_form();
	}
}

// Run the constructor
ES_Jetpack_Subscribe::get_instance();

style.css

#subscribe-blog {
	width: 40%;
	min-width: 250px;
	margin: 30px auto;
}

.subscribe-title {
	font-size: 16px;
	font-family: jaf-domus-titling-web, 'Open Sans', Helvetica, Arial, sans-serif;
	margin: 0 0 10px;
	padding-top: 5px;
	border-top: 4px double #F38630;
}

#subscribe-field {
	width: 96%;
	padding: 6px;
	margin: 2px 0;
	font-size: 30px;
}

#subscribe-submit {
	display: block;
	width: 80%;
	min-width: 50px;
	margin: 2px auto;
	font-size: 16px;
}

@media (max-width: 1050px) {
	.subscribe-title {
		font-size: 14px;
	}

	#subscribe-field {
		font-size: 20px;
	}
}

@media (max-width: 770px) {
	.subscribe-title {
		font-size: 12px;
	}
	#subscribe-field {
		font-size: 16px;
	}
}

@media (max-width: 600px) {
	#subscribe-submit {
		font-size: 14px;
	}
}

Thanks, it works for my website Correctvibe , only made some changes