/* --- CONFIGURACIÓN BASE --- */
* {
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f8f9fa;
    color: #000000;
    line-height: 1.6;
}

.contenedor {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

/* --- ENCABEZADO (HEADER) --- */
header {
    background-color: #1e293b; /* Azul oscuro profesional */
    color: #ffffff;
    padding: 50px 0;
    text-align: center;
    border-bottom: 4px solid #b59410; /* Dorado académico */
}

header h1 {
    margin: 0;
    font-size: 2.2rem;
    letter-spacing: 1px;
}

.subtitulo {
    font-weight: 300;
    margin-top: 10px;
    color: #000000;
}

/* --- MENÚ DE NAVEGACIÓN --- */
.navegacion-principal {
    background-color: #b3ce1b;
    position: sticky;
    top: 0;
    z-index: 100;
}

.navegacion-principal ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
}

.navegacion-principal li {
    margin: 0;
}

.navegacion-principal a {
    display: block;
    padding: 15px 25px;
    color: #ffffff;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    transition: background 0.3s;
}

.navegacion-principal a:hover {
    background-color: #475569;
}

.enlace-activo {
    background-color: #b59410; /* Resalta la página donde estamos */
}

/* --- CONTENIDO Y TARJETAS --- */
main {
    padding: 40px 0;
}

.cabecera-seccion {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
}

.etiqueta-fecha {
    background: #e2e8f0;
    padding: 5px 15px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: bold;
    color: #000000;
}

hr {
    border: 0;
    border-top: 1px solid #cbd5e1;
    margin: 20px 0 40px 0;
}

.tarjeta-articulo {
    background: #ffffff;
    padding: 30px;
    margin-bottom: 25px;
    border-radius: 8px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 30px;
    transition: transform 0.2s;
}

.tarjeta-articulo:hover {
    transform: translateY(-3px);
}

.cuerpo-articulo h3 {
    margin: 0 0 10px 0;
    color: #0f172a;
}

.meta-datos {
    font-style: italic;
    color: #000000;
    font-size: 0.95rem;
}

.resumen {
    font-size: 0.9rem;
    color: #000000;
}

/* --- BOTONES --- */
.boton-pdf {
    background-color: #b91c1c; /* Rojo tipo PDF/Académico */
    color: white;
    padding: 10px 20px;
    text-decoration: none;
    border-radius: 5px;
    font-weight: bold;
    white-space: nowrap;
    transition: background 0.3s;
}

.boton-pdf:hover {
    background-color: #991b1b;
}

/* --- PIE DE PÁGINA --- */
footer {
    background-color: #f1f5f9;
    padding: 40px 0;
    text-align: center;
    color: #64748b;
    font-size: 0.85rem;
    margin-top: 60px;
    border-top: 1px solid #e2e8f0;
}

/* --- RESPONSIVE (MÓVILES) --- */
@media (max-width: 768px) {
    .tarjeta-articulo {
        flex-direction: column;
        align-items: stretch;
        text-align: center;
    }
}