header {
  position: relative;
  background-color: black;
  background: url('https://www.clacso.org.ar/conferencia2018/imagenes/fotos/fondo_cel.jpg') black no-repeat center center scroll;
  background-size:cover;
  height: 75vh;
  min-height: 25rem;
  width: 100%;
  overflow: hidden;
}

header video {
  position: absolute;
  top: 50%;
  left: 50%;
  min-width: 100%;
  min-height: 100%;
  width: auto;
  height: auto;
  z-index: 0;
  -ms-transform: translateX(-50%) translateY(-50%);
  -moz-transform: translateX(-50%) translateY(-50%);
  -webkit-transform: translateX(-50%) translateY(-50%);
  transform: translateX(-50%) translateY(-50%); 
  /*display: none;*/
}

header .container {
  position: relative;
  z-index: 2;
}

header .overlay {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  background-color: black;
  opacity: 0.5;
  z-index: 1;
}


.link_blanco:link {
	color:#FFF;
	font-weight: normal;
	text-decoration: none;
	font-size:22px;
}
.link_blanco:visited {
	color:#FFF;
	font-weight: normal;
	text-decoration: none;
	font-size:22px;
}
.link_blanco:hover {
	color:#0F0;
	font-weight: normal;
	text-decoration: none;
	font-size:22px;
}


.link_blanco2:link {
	color:#FFF;
	font-weight: normal;
	text-decoration: none;
	font-size:2.1vw;
}
.link_blanco2:visited {
	color:#FFF;
	font-weight: normal;
	text-decoration: none;
	font-size:2.1vw;
}
.link_blanco2:hover {
	color:#0F0;
	font-weight: normal;
	text-decoration: none;
	font-size:2.1vw;
}


@media (pointer: coarse) and (hover: none) {
  header {
  /*  background: url('https://source.unsplash.com/XT5OInaElMw/1600x900') black no-repeat center center scroll;*/
	background: url('https://www.clacso.org.ar/conferencia2018/imagenes/fotos/fondo_cel.jpg') black no-repeat center center scroll;
  }
  header video {
    display: none;
  }
}