functions.php

<?php


function open_wrapper() {
  echo '<div class="col-sm-8 col-sm-offset-2">';
}

function close_wrapper() {
  echo '</div>';
}

function single_post_wrapper() {
  if ( is_single() ) {
    add_action( 'shoestrap_single_top', 'open_wrapper', 1 );
    add_action( 'shoestrap_in_article_bottom', 'close_wrapper', 999 );
  }
}
add_action( 'wp', 'single_post_wrapper' );