.filtro{
	position:absolute; 
	bottom:0px; 
	right:0px; 
	filter:opacity(0.2);
}


.texto{
	position:absolute; 
	left:15px; 
	right:15px; 
	bottom:0px; 
	color:white;
	font-size: 175%; 
	font-family:arial;
}

.cuadro-gris{
  transition: 0.5s;
}


.cuadro-gris:hover{

transition: 0.5s;
filter:grayscale(1);

}