custom-buttons-shortcode.php

<?php

    /*

      Plugin Name: Custom Buttons Shortcode
      Description: Add buttons to your WordPress website with single simple shortcode
      Author: Martanian <support@martanian.com>
      Author URI: http://themeforest.net/user/martanian
      Version: 1.0

    */

    add_shortcode( 'custom_buttons_shortcode', 'custom_buttons_shortcode_func' );
    function custom_buttons_shortcode_func( $atts, $content = null ) {

        extract( shortcode_atts( array(
           'href' => '#',
           'target' => '_blank',
           'class' => ''
        ), $atts ));

        return( '<div class="custom-buttons-shortcode-container"><a href="'. esc_url( $href ) .'" target="'. esc_attr( $target ) .'" class="custom-buttons-shortcode '. esc_attr( $class ) .'">'. do_shortcode( $content ) .'</a></div>' );
    }

    add_action( 'wp_enqueue_scripts', 'custom_buttons_shortcode_styles' );
    function custom_buttons_shortcode_styles() {

        wp_enqueue_style( 'custom-buttons-shortcode-style', plugin_dir_url( __FILE__ ) .'style.css' );
    }

?>

example-usage.txt

# all params example
[custom_buttons_shortcode href="http://example.com" target="_self" class="extra-class"]Hello![/custom_buttons_shortcode]

# only "href" is required
[custom_buttons_shortcode href="http://example.com"]Hello![/custom_buttons_shortcode]

style.css

.custom-buttons-shortcode-container {
    margin: 30px 0;
}

.custom-buttons-shortcode-container .custom-buttons-shortcode {
    display: inline-block; 
    text-align: center; 
    padding: 10px 25px; 
    background: #e73a30; 
    color: #fff; 
    font-size: 17px; 
    -webkit-border-radius: 2px; 
    -moz-border-radius: 2px; 
    border-radius: 2px; 
    border-bottom: 2px solid #b7241b; 
}