body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    text-align: center;
    background-color: #333;
    color: white;
    padding: 1em 0;
}

main {
    padding: 2em;
    max-width: 1200px;
    margin: auto;
}

#portadas {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
}

.revista {
    margin: 1em;
    text-align: center;
}

.miniatura {
    width: 150px;
    height: auto;
    border: 1px solid #ccc;
}

footer {
    text-align: center;
    padding: 1em 0;
    background-color: #333;
    color: white;
    position: absolute;
    width: 100%;
    bottom: 0;
}

@media (max-width: 768px) {
    .revista {
        width: 100%;
    }
}