body{
    background-image: url(img/2b.1.jpg);
    background-attachment: fixed;
    background-repeat: no-repeat;
    background-position: center center;
    background-size:cover;
}
div#nav-fijo {
    position: fixed;
    top: 0;
    width: 100%;
    height: 70px;
    background-color: gray;
    box-shadow: 0 2px 4px black;
    border: 1px outset black;
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 40px;
    z-index: 1000;
}

#nav-fijo a {
    text-decoration: none;
    color: black;
    font-weight: bold;
    transition: color 0.3s;
}

#nav-fijo a:hover {
    color: white;
}

div#contenido {
    margin-top: 90px;
    padding: 20px;
}

div#contenedor-cuadricula {
    width: 1300px;
    margin: auto;
    margin-top: 20px;
    overflow: hidden;
}

div.cuadro {
    float: left;
    width: 400px;
    height: 200px;
    margin: 15px;
    background-color: #ffffff36;
    border: 1px outset black;
    box-shadow: 0 2px 4px black;
    text-align: center;
    line-height: 200px;
    font-weight: bold;
    transition: all 0.3s ease;
}

div.cuadro:hover {
    background-color: #8080809c;
    box-shadow: 0 2px 4px white;
    border: 1px outset white;
    transform: scale(1.05);
}