/* ===============================
   estilo general
   =============================== */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.6;
    color: #333;
}

/* ===============================
   encabezado y navegación
   =============================== */

   header {
    background-color: #2f4f4f;
    padding: 15px 0;
}

nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
}
   
.barra-navegacion {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 30px;
}

.logo-titulo {
    flex: 1;
    padding: 20px;
    background-color: #f4f4f4;
    text-align: center;
}

.menu {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
}

.menu li {
    margin: 5px 15px;
}

.menu li a {
    text-decoration: none;
    color: #ffffff;
    font-weight: bold;
}

.menu li a:hover {
    text-decoration: underline;
}

/* ===============================
   contenido
   =============================== */

main {
    padding: 30px;
}

.contenido-principal {
    display: flex;
    gap: 20px;
}

/* Columnas del contenido */
.columna {
    flex: 1;
    padding: 20px;
    background-color: #f4f4f4;
    text-align: center;
}

.columna img {
    max-width: 100%;
    height: auto;
    margin-top: 15px;
}

/* ===============================
   footer
   =============================== */

footer {
    background-color: #2f4f4f;
    color: #ffffff;
    padding: 30px 20px;
}

.footer-contenido {
    display: flex;
    gap: 20px;
}

.footer-columna {
    flex: 1;
    text-align: center;
}

.footer-columna img {
    width: 30px;
    margin: 5px;
}

/* ===============================
   Media queries
   =============================== */

/* TABLET (pantallas medianas) */
@media (max-width: 900px) {

    .contenido-principal {
        flex-direction: column;
    }

    .footer-contenido {
        flex-direction: column;
    }
}

/* télefono (pantallas pequeñas) */
@media (max-width: 600px) {

    .barra-navegacion {
        flex-direction: column;
        text-align: center;
    }

    .logo-titulo {
        margin-bottom: 10px;
    }

    .menu {
        flex-direction: column;
        align-items: center;
    }

    .menu li {
        margin: 8px 0;
    }
}