JSFiddle - React, Tailwind, and code Playground

HTML

<a href="http://www.digitarts.it">DigitArts.it</a><br>
<a href="mailto:[email protected]">Email</a><br>
<a href="http://www.nomedominio.it/file.pdf">PDF</a>

CSS

/* external links */
a[href^="http://"] {
    padding-right: 13px;
    background: url('http://identifyla.lsu.edu/images/icon_web.png') no-repeat center right;
}

/* emails */
a[href^="mailto:"] {
    padding-right: 20px;
    background: url('http://png-2.findicons.com/files/icons/1722/gnome_2_18_icon_theme/24/evolution_mail.png') no-repeat center right;
}

/* pdfs */
a[href$=".pdf"] {
    padding-right: 18px;
    background: url('http://www.wqa.com/wp-content/uploads/2011/07/pdf-icon-24x24.png') no-repeat center right;
}