header posts page 2011 child

@@hreplace this section in header.php:
            <?php
                // Check to see if the header image has been removed
                $header_image = get_header_image();
                if ( $header_image ) :
                    // Compatibility with versions of WordPress prior to 3.4.
                    if ( function_exists( 'get_custom_header' ) ) {
                        // We need to figure out what the minimum width should be for our featured image.
                        // This result would be the suggested width if the theme were to implement flexible widths.
                        $header_image_width = get_theme_support( 'custom-header', 'width' );
                    } else {
                        $header_image_width = HEADER_IMAGE_WIDTH;
                    }
                    ?>
            <a href="<?php echo esc_url( home_url( '/' ) ); ?>">
                <?php
                    // The header image
                    // Check if this is a post or page, if it has a thumbnail, and if it's a big one
                    if ( is_singular() && has_post_thumbnail( $post->ID ) &&
                            ( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), array( $header_image_width, $header_image_width ) ) ) &&
                            $image[1] >= $header_image_width ) :
                        // Houston, we have a new header image!
                        echo get_the_post_thumbnail( $post->ID, 'post-thumbnail' );
                    else :


@@hwith:
                <?php
                    // The header image
                    // Check if this is a post or page, if it has a thumbnail, and if it's a big one
                    if( is_singular() ) $post_id = $post->ID;
                    elseif ( is_home() && get_option('page_for_posts') ) $post_id = get_option('page_for_posts');
                    if ( ( is_singular() || is_home() && get_option('page_for_posts') ) &&
                            has_post_thumbnail( $post_id ) &&
                            ( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post_id ), array( $header_image_width, $header_image_width ) ) ) &&
                            $image[1] >= $header_image_width ) :
                        // Houston, we have a new header image!
                        echo get_the_post_thumbnail( $post_id, 'post-thumbnail' );
                    else :