:root {
    --primary: #FFB400; /* Amarillo construcción */
    --dark: #1A1A1B;    /* Negro industrial */
    --gray: #F4F4F4;    /* Gris cemento claro */
    --white: #FFFFFF;
    --text: #333333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', sans-serif;
}

body {
    line-height: 1.6;
    color: var(--text);
    background-color: var(--white);
}

/* --- NAVEGACIÓN --- */
header {
    background: var(--white);
    padding: 1rem 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.logo {
    font-weight: 900;
    font-size: 1.5rem;
    color: var(--dark);
    text-transform: uppercase;
}

.logo span { color: var(--primary); }

nav ul {
    display: none; /* Mobile-first: oculto en móvil */
}

/* --- HERO SECTION --- */
.hero {
    height: 90vh;
    background: linear-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.5)), 
                url('https://images.unsplash.com/photo-1503387762-592dee58c460?q=80&w=1600&auto=format&fit=crop');
    background-size: cover;
    background-position: center;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 0 20px;
    color: var(--white);
}

.hero h1 {
    font-size: 2.5rem;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    text-transform: uppercase;
}

.hero p {
    font-size: 1.1rem;
    margin-bottom: 2rem;
    max-width: 600px;
}

.btn-main {
    background: var(--primary);
    color: var(--dark);
    padding: 1rem 2rem;
    text-decoration: none;
    font-weight: bold;
    text-transform: uppercase;
    transition: 0.3s;
}

/* --- ESTADÍSTICAS (BARRA AMARILLA) --- */
.stats {
    background: var(--primary);
    display: grid;
    grid-template-columns: repeat(2, 1fr); /* 2x2 en móvil */
    padding: 2rem 1rem;
    gap: 1.5rem;
    text-align: center;
}

.stat-item h3 { font-size: 1.8rem; color: var(--dark); }
.stat-item p { font-size: 0.8rem; font-weight: bold; text-transform: uppercase; }

/* --- SERVICIOS BREVES --- */
.brief-services {
    padding: 4rem 5%;
}

.section-head {
    text-align: center;
    margin-bottom: 3rem;
}

.section-head h2 { font-size: 2rem; text-transform: uppercase; }
.section-head div { 
    width: 60px; height: 4px; background: var(--primary); margin: 10px auto; 
}

.services-grid {
    display: grid;
    grid-template-columns: 1fr; /* 1 columna en móvil */
    gap: 20px;
}

.service-card {
    border: 1px solid #ddd;
    padding: 2rem;
    transition: 0.3s;
}

.service-card:hover { border-color: var(--primary); }

/* --- MEDIA QUERIES (ESCRITORIO) --- */
@media (min-width: 768px) {
    nav ul {
        display: flex;
        list-style: none;
    }
    nav ul li { margin-left: 2rem; }
    nav ul li a { text-decoration: none; color: var(--dark); font-weight: 600; transition: 0.3s; }
    nav ul li a:hover { color: var(--primary); }

    .hero h1 { font-size: 4.5rem; }
    
    .stats {
        grid-template-columns: repeat(4, 1fr); /* 4 en línea en escritorio */
        transform: translateY(-50px);
        width: 80%;
        margin: 0 auto -50px auto;
        border-radius: 4px;
    }

    .services-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}


/* --- NUEVAS SECCIONES DETALLADAS --- */
.detail-section {
    display: flex;
    flex-direction: column; /* Mobile-first: apilado vertical */
    align-items: center;
    gap: 2rem;
    padding: 4rem 5%;
}

.detail-content {
    flex: 1;
}

.detail-content h2 {
    font-size: 1.8rem;
    color: var(--dark);
    margin-bottom: 1rem;
    text-transform: uppercase;
}

.detail-image {
    flex: 1;
    width: 100%;
}

.detail-image img {
    width: 100%;
    height: 350px;
    object-fit: cover;
    border-radius: 4px;
    box-shadow: 10px 10px 0px var(--primary); /* Detalle estético industrial */
}

.bg-light {
    background-color: var(--gray);
}

/* --- MEDIA QUERIES PARA ESCRITORIO (ZIG-ZAG) --- */
@media (min-width: 768px) {
    .detail-section {
        flex-direction: row; /* Lado a lado en escritorio */
        gap: 5rem;
    }

    /* Clase para invertir el orden y crear el efecto zig-zag */
    .row-reverse {
        flex-direction: row-reverse;
    }

    .detail-content h2 {
        font-size: 2.5rem;
    }
}

/* Clase para el menú activo */
nav ul li a.active {
    color: var(--primary); /* El amarillo que estamos usando */
    border-bottom: 2px solid var(--primary);
    padding-bottom: 5px;
}