Phone and mail don't show up. Twitter icon shows up but the rest of them aren't

/*********************************************************** Page Contacto ***********************************************************/

.contacto-info { list-style: none; padding: 0; margin: 0; font-size: 0.9em; }

.contacto-info a { display: block; min-height: 20px; background-repeat: no-repeat; background-size: 20px 20px; padding: 0 0 0 30px; margin: 0 0 10px; }

.contacto-info li.Twitter a { background-image: url('/img/twitter.png') }

.contacto-info li.Telefono a { background-image: url('/img/Telefono.png') }

.contacto-info li.Mail a { background-image: url('/img/mail.png') }

Contacto.html

<ul class="contacto-info"> <li class"Telefono"> <a href="Tel: 81-1916-2937">81-1916-2937</a></li> <li class"Mail"><a href="mailto: cdge.mmind@gmail.com "> cdge.mmind@gmail.com </a></li> <li class="Twitter"><a href="https://twitter.com/intent/tweet?screen_name=CesarDGzz">@CesarDGzz</a></li> </ul> </section>