/* ----------- reglas generales y módulos ----------- */

* {
    box-sizing: border-box;
}

body {
    background-color: rgba(255, 255, 255, 0.1);
    margin: 0;
    font-family: "trebuchet ms", sans-serif;
}

header,
footer {
    background-color: rgba(67, 61, 64, 0.35);
}

img {
    max-width: 100%;
    height: auto;
}

.contenedor,
main > section {
    max-width: 40rem;
    margin: 0 auto;
    padding: 1rem;
}



/* ----------- header ----------- */

nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    background-color: rgba(0, 0, 0, 0.2);
}

nav ul li a {
    background-color: rgba(0, 0, 0, 0.5);
    color: white;
    font-weight: bold;
    text-decoration: none;
}



/* ----------- main ----------- */

main > section {
    background-color: white;
    border: solid 1px lightblue;
    border-radius: 1rem;
    box-shadow: 0 2px 2px 2px rgba(0, 0, 0, 0.125);
    margin-top: 1em;
    margin-bottom: 1em;
}

main > section > h1,
main > section > h2 {
    border-bottom: solid .25em rgba(170, 170, 170, 0.35);
    margin-top: 0;
    padding-bottom: .25em;
}