WordPress: Remove inline styling of captions, helpful for responsive themes.

remove-caption-style.php

add_shortcode('wp_caption', 'fixed_img_caption_shortcode');
add_shortcode('caption', 'fixed_img_caption_shortcode');
function fixed_img_caption_shortcode($attr, $content = null) {
  // Allow plugins/themes to override the default caption template.
	$output = apply_filters('img_caption_shortcode', '', $attr, $content);
	if ( $output != '' ) return $output;
	extract(shortcode_atts(array(
		'id'=> '',
		'align'	=> 'alignnone',
		'width'	=> '',
		'caption' => ''), $attr));
	if ( 1 > (int) $width || empty($caption) )
	return $content;
	if ( $id ) $id = 'id="' . esc_attr($id) . '" ';
	return '<div ' . $id . 'class="wp-caption ' . esc_attr($align)
	. '">'
	. do_shortcode( $content ) . '<p class="wp-caption-text">'
	. $caption . '</p></div>';
}