.btn_pdf,
.btn_pdf:visited,
.btn_ppt:visited 
{display: inline-block;
padding: 1em 1.5em;
text-decoration: none;
color: #FFF;
border-radius: 10px;
transition: .3s;
line-height: 120%;
background-color: #900;
}




.btn:hover,
.btn_pdf:hover,
.btn_word:hover,
.btn_ppt:hover
{background: #f00;
color: #fff;
text-decoration: none;
}




.btn_word,
.btn_word:visited
{display: inline-block;
padding: 1em 1.5em;
text-decoration: none;
color: #FFF;
border-radius: 10px;
transition: .3s;
line-height: 120%;
background-color: #069;
}


.btn_ppt,
.btn_ppt:visited
{
	display: inline-block;
	padding: 1em 1.5em;
	text-decoration: none;
	color: #FFF;
	border-radius: 10px;
	transition: .3s;
	line-height: 120%;
	background-color: #F63;
}

.shadow {
        filter: drop-shadow(3px 3px 3px #aaa);
}