body {
    font-family: system-ui, -apple-system, sans-serif;
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem;
    background: #f5f5f5;
    color: #222;
}
h1 {
    font-size: 1.5rem;
    margin-bottom: .5rem;
}
.card-producto {
    background: #fff;
    border-radius: 8px;
    padding: 1.25rem 1.5rem;
    margin-bottom: 1rem;
    box-shadow: 0 1px 3px rgba(0,0,0,.08);
    display: flex;
    align-items: center;
    gap: 1.5rem;
}
.titulo-producto {
    font-size: 1rem;
    margin: 0;
    flex: 1;
    color: #111;
}
.precio {
    font-weight: 600;
    color: #2b6e2b;
}
.disponibilidad {
    font-size: .85rem;
    padding: 2px 10px;
    border-radius: 12px;
}
.en-stock {
    background: #e6f4e6;
    color: #1a5a1a;
}
.sin-stock {
    background: #fde8e8;
    color: #a11f1f;
}
.enlace-detalle {
    font-size: .85rem;
    color: #1a5bb5;
    text-decoration: none;
}
.enlace-detalle:hover {
    text-decoration: underline;
}

/* Navegación entre niveles */
.nav-niveles {
    display: flex;
    gap: .25rem;
    margin-bottom: 2rem;
    background: #fff;
    padding: .5rem;
    border-radius: 8px;
    box-shadow: 0 1px 3px rgba(0,0,0,.08);
}
.nav-niveles a,
.nav-niveles span {
    padding: .35rem .85rem;
    border-radius: 6px;
    font-size: .9rem;
    text-decoration: none;
}
.nav-niveles a {
    color: #555;
}
.nav-niveles a:hover {
    background: #eee;
}
.nav-niveles span {
    background: #222;
    color: #fff;
    font-weight: 500;
}

/* Level labels */
.nivel-label {
    font-size: .75rem;
    font-weight: 600;
    padding: 2px 8px;
    border-radius: 10px;
    vertical-align: middle;
}
.nivel-label.facil {
    background: #e6f4e6;
    color: #1a5a1a;
}
.nivel-label.medio {
    background: #fff3cd;
    color: #856404;
}
.nivel-label.dificil {
    background: #fde8e8;
    color: #a11f1f;
}
.nivel-desc {
    font-size: .9rem;
    color: #666;
    margin-bottom: 1.5rem;
}

/* Paginación */
.paginacion {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 1rem;
    margin-top: 1.5rem;
}
.btn-pag {
    background: #fff;
    border: 1px solid #ccc;
    border-radius: 6px;
    padding: .5rem 1rem;
    cursor: pointer;
    font-size: .9rem;
}
.btn-pag:hover:not(:disabled) {
    background: #eee;
}
.btn-pag:disabled {
    opacity: .4;
    cursor: default;
}

/* Loader */
.loader {
    text-align: center;
    padding: 2rem;
    color: #888;
    font-style: italic;
}

/* Hero / landing */
.hero-desc {
    font-size: 1rem;
    color: #555;
    margin-bottom: 2rem;
}
.nivel-card {
    background: #fff;
    border-radius: 8px;
    padding: 1.25rem 1.5rem;
    margin-bottom: 1rem;
    box-shadow: 0 1px 3px rgba(0,0,0,.08);
    cursor: pointer;
    transition: box-shadow .15s;
}
.nivel-card:hover {
    box-shadow: 0 2px 8px rgba(0,0,0,.12);
}
.nivel-card h2 {
    font-size: 1.1rem;
    margin: 0 0 .35rem;
    display: flex;
    align-items: center;
    gap: .5rem;
}
.nivel-card p {
    margin: 0;
    font-size: .9rem;
    color: #555;
}