body 
{
    background-color: burlywood;
}

#IA_1
{
    width: 500px;
    height: 300px;
    position: relative;
    top:20px;
    left:100px;
}

#IA_2
{
    width: 500px;
    height: 300px;
    position: relative;
    bottom: 495px;
    left:650px;
}

.tarjeta
{
    background-color: brown;
    position: relative;
    top:-250px;
    left:150px;
    width: 400px;
    height: 400px;
}

.tarjeta p,h3 
{
    font-size: 50px;
}


.bloque
{
     background-color: blue;
     position: relative;
     bottom: 665px;
     left:600px;
     color:white;
     width: 400px;
    height: 400px;
}

nav li
{
    list-style: none;/*quitar alguna viñeta que tenga el li*/
    display:inline-block;/*sirve para ponerlo en forma de caja horizontal*/
    padding: 4px 80px;
    text-align: center;
    background-color: brown;
    font-size: 30px;
    position: relative;
    left:100px;
    
}

nav a
{
    text-decoration: none;
    color:white;
    font-weight: bold;
}