#contenedor{
    text-align: left;
    width: 800px;
    margin: auto; /* Con esto centra esta capa en IE y Firefox */
}

.titulo_indice{
   /* margin-left: 40px; /* 7%;*/ /* auto; *//*20%;*/
    margin: auto;
    width: 700px; /* 82%; /*con menos anchura en IE pone 2 líneas a 800x600 */
    border-style: groove; /* inset;*/
    border-color: blue;
    border-width: 18px; 
    font-family: Georgia, "Times New Roman", Serif;
    font-size: 36px;/*32px;*/
    text-align: center;
    text-decoration: underline;
}
.titulo{
   /* margin-left: 14%; /* auto; *//*20%;*/
    margin: auto;
    width: 530px; /*con menos anchura en IE pone 2 líneas a 800x600 */
    border-style: groove; 
    border-color: blue;
    border-width: 18px; 
    font-family: Georgia, "Times New Roman", Serif;
    font-size: 32px;
    text-align: center;
    text-decoration: underline;
}
.nota{
    margin-left: 135px;
    margin-right: 30px;
}
.imagen{
    margin: 0.30cm;
    border-style: solid;
    border-width: 2px;
    border-color: black;
}
.imagen_1{
   margin-left: 3cm;
   margin-right: 0.30cm;
   margin-top: 0.30cm;
   margin-bottom: 0.30cm;
   border-style: solid;
   border-width: 2px;
   border-color: black;
}
.lista_notas{
    margin-left: 225px;
    font-size: 24px;
}
#cuerpo_principal{
    position: absolute;
    width: 790px;
    float: left; /* */
}
.volver{
  position: fixed;
  top: 210px;
  left: 20px; /* 350px;*/
  border-style: inset;
  border-width: 15px;
  font-size: 25px;
  font-align: left;
  font-weight: bold;
}
.volver_2{
  position: absolute;
  top: 60px;
  left: 100px; /* 350px;*/
  border-style: inset;
  border-width: 15px;
  font-size: 25px;
  font-align: left;
  font-weight: bold;
}
.volver_3{
  position: absolute;
  top: 90px;
  left: 10px; /* 350px;*/
  border-style: inset;
  border-width: 15px;
  font-size: 25px;
  font-align: left;
  font-weight: bold;
}
.volver_4{
  position: absolute;
/*  top: 650px;*/
  left: 10px; /* 350px;*/
  border-style: inset;
  border-width: 15px;
  font-size: 25px;
  font-align: left;
  font-weight: bold;
}

.fondo_nota{
  background-color: rgb(245, 240, 185);
  text-align: center;
}