* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}
body {
    background-color: #f7f9fa;
    color: #2c3e50;
    line-height: 1.6;
}
header {
    background-color: #e87b1e;
    color: #ffffff;
    padding: 1.5rem 0;
    text-align: center;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
nav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-top: 15px;
    flex-wrap: wrap;
}
nav a {
    color: #ffffff;
    text-decoration: none;
    font-weight: 600;
    padding: 5px 10px;
    border-radius: 4px;
    transition: background-color 0.3s ease;
}
nav a:hover, nav a.active-link {
    background-color: #8cc63f;
}
main {
    padding: 40px 20px;
    max-width: 900px;
    margin: 0 auto;
    min-height: 60vh;
}

/* Control de visibilidad y animaciones - Tarjetas */
.tarjeta-inactiva {
    display: none;
}
.tarjeta-activa {
    display: block;
    background: #ffffff;
    border-radius: 8px;
    box-shadow: 0 8px 16px rgba(0,0,0,0.1);
    padding: 35px;
    border-top: 10px solid #8cc63f;
    animation: entradaSuave 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94) both;
}

@keyframes entradaSuave {
    0% {
        opacity: 0;
        transform: translateY(30px) scale(0.98);
    }
    100% {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.tarjeta-activa h2 {
    color: #e87b1e;
    margin-bottom: 25px;
    text-align: center;
    font-size: 2.5rem;
}
.comparativa-fotos {
    display: flex;
    gap: 20px;
    margin-bottom: 25px;
}
.foto-espacio {
    background-color: #e9ecef;
    flex: 1;
    height: 250px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    border-radius: 8px;
    border: 2px dashed #adb5bd;
    padding: 15px;
}
.foto-espacio span {
    font-size: 0.9rem;
    color: #6c757d;
}
ul { list-style-type: none; }
li {
    margin-bottom: 15px;
    padding-left: 20px;
    position: relative;
    font-size: 1.1rem;
    text-align: justify;
}
li::before {
    content: "•";
    color: #8cc63f;
    font-weight: bold;
    font-size: 1.5rem;
    position: absolute;
    left: 0;
    top: -4px;
}

/* Responsivo */
@media (max-width: 768px) {
    .comparativa-fotos {
        flex-direction: column;
    }
    .foto-espacio {
        height: 200px;
    }
    .tarjeta-activa h2 {
        font-size: 2rem;
    }
}

/* Footer Bibliográfico */
footer {
    background-color: #2c3e50;
    color: #ffffff;
    padding: 40px 20px;
    margin-top: 40px;
    min-height: 250px;
}
footer h3 {
    text-align: center;
    margin-bottom: 25px;
    color: #8cc63f;
}

/* Control de visibilidad - Bibliografías */
.bloque-biblio.biblio-inactiva {
    display: none;
}
.bloque-biblio.biblio-activa {
    display: block;
    animation: entradaSuave 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94) both;
}

.bloque-biblio p {
    max-width: 800px;
    margin: 0 auto 10px auto;
    color: #e87b1e;
    font-size: 1.2rem;
    text-align: center;
}
.bloque-biblio ol {
    max-width: 800px;
    margin: 0 auto 25px auto;
    padding-left: 40px;
    font-size: 0.9rem;
}
.bloque-biblio li::before { display: none; }
.bloque-biblio li { text-align: left; }