h1 {
  text-align:center;
}
p{
  font-family:serif;
}
#primer-parrafo{
  background-color:#CEE;
}
p.primer-parrafo em{
    color:#933;}
a {
  outline: 1px solid #333
  }
p.fuente{
  opacity: 100%;
  color: #000;
  }
p:not([id]) {
  background-color: rgba(190, 120, 240, 0.6);
}
.complicado{
  color: #C62; 
  font-weight: bold;
  }