* {
    margin: 0;
    padding: 0;
    font-size: 20px;
    font-family: Georgia, 'Times New Roman', Times, serif;
    line-height: 1.5;
}

h1 {
    font-size: 40px;
    text-align: center;
    font-style: italic;
    padding-top: 25px;
    padding-bottom: 50px;
}

.caja1 {
    margin: auto;
    width: 50%;
    text-align: justify;
    background-color:mediumpurple;
}

.caja2 {
    margin: auto;
    width: 50%;
    text-align: justify;
    background-color:mediumseagreen;
    padding-right: 150px;
    padding-left: 150px;
}

.caja3 {
    margin: auto;
    width: 50%;
    text-align: justify;
    background-color: mediumaquamarine;
    padding-right: 150px;
    padding-left: 150px;
    box-sizing: border-box;
}

.claseSpan {
    font-weight: bold;
    font-style: italic;
}