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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: #333;
    line-height: 1.6;
}

/* Header & Navegación */
.encabezado-principal {
    background-color: #ffffff;
    padding: 15px 5%;
    border-bottom: 1px solid #eee;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#logo {
    color: #1a252f;
    font-size: 1.8rem;
}

#logo span {
    color: #3498db;
}

.menu-nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}

.menu-nav a {
    text-decoration: none;
    color: #2c3e50;
    font-weight: 600;
    display: inline-block;
    padding: 5px 10px;
}

/* Banner Notificación */
.baner-notificacion {
    background-color: burlywood;
    color: aliceblue;
    text-align: center;
    padding: 10px 15px;
    border-bottom: 3px solid #d35400;
    font-weight: bolder;
    font-size: 0.9rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

/* Sección Hero */
.hero-principal {
    background: linear-gradient(135deg, #2c3e50, #3498db);
    color: #ffffff;
    text-align: center;
    padding: 60px 20px;
}

.hero-principal h2 {
    color: #ffffff;
    font-size: 2rem;
    margin-bottom: 10px;
}

.hero-principal p {
    color: #ecf0f1;
}

/* Botón Principal */
.btn-principal {
    background-color: #27ae60;
    color: #ffffff;
    border: none;
    padding: 12px 25px;
    border-radius: 5px;
    font-size: 1rem;
    font-weight: bold;
    margin-top: 15px;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.btn-principal:hover {
    background-color: #219150;
}

.btn-principal:focus {
    outline: 3px solid #f1c40f;
}

/* Sección Cursos y Grid */
.seccion-cursos {
    padding: 40px 5%;
}

.seccion-cursos h2 {
    color: #2c3e50;
    margin-bottom: 20px;
}

.grid-cursos {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 25px;
    margin-top: 20px;
}

/* Tarjetas */
.tarjeta-cursos {
    background-color: #ffffff;
    padding: 25px;
    border: 1px solid #e0e0e0;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.tarjeta-cursos h3 {
    font-size: 1.4rem;
    color: #2c3e50;
    margin-bottom: 10px;
}

.tarjeta-cursos:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 20px rgba(0, 0, 0, 0.15);
}

/* Tarjeta Destacada */
.tarjeta-cursos.destacado {
    border: 2px solid #3498db;
    position: relative;
}

.tarjeta-cursos.destacado::before {
    content: "¡MÁS POPULAR!";
    position: absolute;
    top: -13px;
    right: 12px;
    background-color: #e74c3c;
    color: #ffffff;
    font-size: 0.7rem;
    font-weight: bold;
    padding: 3px 8px;
    border-radius: 3px;
}

.precio {
    display: inline-block;
    margin-top: 15px;
    font-size: 1.2rem;
    font-weight: bold;
    color: #27ae60;
}

/* Pie de página */
.pie-pagina {
    background-color: #1a252f;
    color: #ffffff;
    text-align: center;
    padding: 20px;
    margin-top: 40px;
}

/* Diseños Responsivos */
@media (max-width: 768px) {
    .encabezado-principal {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }

    .hero-principal h2 {
        font-size: 1.5rem;
    }

    .grid-cursos {
        grid-template-columns: 1fr;
    }
}