style attribute problem im form submit

Please someone help my error.
In my project i use tinymce,codeigniter 3.1.9
i create a form which use tinymce.
Everything is fine if i type texts in tinymce editor and submit form.
The problem is that i tried to text-align the texts  i typed and submit the form but there i got empty post when i print_r the $_POST.
What might be the problem