Stop WordPress removing HTML. Add the bellow code on your functions.php
/**
*
* Stop tiny_mce removing html
*/
if ( ! function_exists( 'ns_override_mce_options' ) ) {
function ns_override_mce_options( $initArray ) {
$opts = '*[*]';
$initArray[ 'valid_elements' ] = $opts;
$initArray[ 'extended_valid_elements' ] = $opts;
return $initArray;
}
add_filter( 'tiny_mce_before_init', 'ns_override_mce_options' );
}