* {
    box-sizing: border-box;
}

body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: hsl(224, 86%, 80%);
}

h1 {
    text-align: center;
    color: #000000;
    font-size: 36px;
}

h2 {
    text-align: center;
    color: #000000;
    font-size: 30px;
    font-family: 'Times New Roman', serif;
}

nav {
    background-color: #152b47;
    padding: 10px;
    text-align: center;
}

nav a {
    color: white;
    text-decoration: none;
    margin-right: 15px;
    font-size: 12px;
}

.contenedor {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    padding: 20px;
}
.contenedor {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
    padding: 20px;
}

section {
    background-color: #ddf5fc;
    border: 1px solid #7098b3;
    border-radius: 5px;
    padding: 10px;
    margin-bottom: 20px;
    width: 300px;
}

button {
    background-color: #486ea0;
    color: white;
    border: none;
    padding: 10px 20px;
    cursor: pointer;
    margin-top: 10px;
}

footer {
    background-color: #152b47;
    color: white;
    text-align: center;
    padding: 10px;
    /* Nota: 'position: center' no es una propiedad válida. 
       Si querías fijarlo al fondo, usa 'position: fixed; bottom: 0;' */
    width: 100%;
}

section img {
    width: 100%;
    height: auto;
}