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

body {
    font-family: Arial, Helvetica, sans-serif;
    background-color: #f1f5f9;
    color: #334155;
    line-height: 1.6;
}

/* ENCABEZADO */
.encabezado-principal {
    background-color: #0f172a;
    padding: 18px 5%;
    border-bottom: 2px solid #2563eb;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

#logo span {
    color: #06b6d4;
}

/* MENÚ DE NAVEGACIÓN */
.menu-nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}

.menu-nav a {
    text-decoration: none;
    color: #e2e8f0;
    font-weight: 600;
    display: inline-block;
    padding: 8px 14px;
    border-radius: 6px;
    transition: all 0.3s ease;
}

.menu-nav a:hover {
    background-color: #2563eb;
    color: white;
}

/* BANNER DE OFERTA */
.banner-oferta {
    background: linear-gradient(
        90deg,
        #7c3aed,
        #2563eb
    );
    color: white;
    text-align: center;
    padding: 12px 15px;
    border-bottom: 3px solid #06b6d4;
    font-weight: bold;
    font-size: 1rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

/* SECCIÓN PRINCIPAL */
.hero {
    background: linear-gradient(
        135deg,
        #0f172a,
        #1e3a8a,
        #4338ca
    );
    color: white;
    padding: 80px 20px;
    text-align: center;
}

.hero h2 {
    color: #ffffff;
    font-size: 2.5rem;
    margin-bottom: 15px;
}

.hero .subtitulo {
    color: #cbd5e1;
    font-size: 1.1rem;
}

/* BOTÓN PRINCIPAL */
.btn-principal {
    background-color: #06b6d4;
    color: #0f172a;
    border: none;
    padding: 15px 28px;
    font-size: 1rem;
    font-weight: bold;
    border-radius: 8px;
    margin-top: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.btn-principal:hover {
    background-color: #22d3ee;
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(6,182,212,0.3);
}

.btn-principal:focus-visible {
    outline: 3px solid #facc15;
    outline-offset: 3px;
}

/* SECCIÓN CURSOS */
.seccion-cursos {
    padding: 60px 5%;
}

.seccion-cursos h2 {
    text-align: center;
    font-size: 2rem;
    color: #0f172a;
    margin-bottom: 30px;
}

/* GRID DE CURSOS */
.grid-cursos {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 25px;
    margin-top: 20px;
}

/* TARJETAS */
.tarjeta-curso {
    background-color: #ffffff;
    width: 100%;
    padding: 30px 25px;
    border: 1px solid #e2e8f0;
    border-radius: 12px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
    transition: transform 0.3s ease,
                box-shadow 0.3s ease;
}

.tarjeta-curso:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 25px rgba(37,99,235,0.18);
}

.tarjeta-curso h3 {
    font-size: 1.4rem;
    color: #1e3a8a;
    margin-bottom: 12px;
}

.tarjeta-curso p {
    color: #64748b;
}

/* PRECIOS */
.precio {
    display: inline-block;
    margin-top: 20px;
    font-size: 1.4rem;
    font-weight: bold;
    color: #059669;
}

/* CURSO DESTACADO */
.tarjeta-curso.destacado {
    border: 2px solid #7c3aed;
    position: relative;
}

.tarjeta-curso.destacado::before {
    content: "MÁS POPULAR";
    position: absolute;
    top: -14px;
    right: 15px;
    background-color: #7c3aed;
    color: white;
    padding: 6px 12px;
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: bold;
}

/* PIE DE PÁGINA */
.pie-pagina {
    background-color: #0f172a;
    color: #cbd5e1;
    text-align: center;
    padding: 25px;
    margin-top: 40px;
}

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

    .menu-nav ul {
        justify-content: center;
        flex-wrap: wrap;
        gap: 8px;
    }

    .hero h2 {
        font-size: 1.8rem;
    }

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

    .seccion-cursos {
        padding: 45px 5%;
    }
}