.fondo
{
  background-image: url("gidi-1.png");
  background-size:cover;
  background-repeat: no-repeat;
  background-attachment: fixed;
}
.fondo::before
{
  opacity: 0.25;
}

p {
    margin-bottom: 15px;
    text-indent: 1.5em;
    text-align: justify;
    margin-top: 0;
}

.negrita {
  font-weight: bold;
}


h3 {
   color: red;
}

h4 {
  color: blue;
}

a {
  color: green;
}