:root {
    --primary-color: #0d253f; /* Xanh đậm công nghiệp */
    --accent-color: #f39c12;  /* Màu cam xây dựng/năng lượng */
    --text-gray: #6c757d;
    --light-bg: #f8f9fa;
}

body {
    font-family: 'Roboto', sans-serif;
    color: #333;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    font-family: 'Montserrat', sans-serif;
    font-weight: 700;
}

/* --- NAVBAR --- */
.navbar {
    background-color: var(--primary-color);
    padding: 15px 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}
.navbar-brand {
    font-weight: 700;
    font-size: 24px;
    color: white !important;
}
.navbar-brand span { color: var(--accent-color); }
.nav-link {
    color: rgba(255,255,255,0.8) !important;
    font-weight: 500;
    margin-left: 15px;
    transition: 0.3s;
}
.nav-link:hover, .nav-link.active {
    color: var(--accent-color) !important;
}
.btn-quote {
    background-color: var(--accent-color);
    color: white;
    border-radius: 0;
    padding: 8px 25px;
    font-weight: 600;
    transition: 0.3s;
}
.btn-quote:hover {
    background-color: #d68910;
    color: white;
}

/* --- HERO SECTION --- */
.hero {
    height: 100vh;
    background: linear-gradient(rgba(13, 37, 63, 0.7), rgba(13, 37, 63, 0.6)),
                url('about/1.jpg?auto=format&fit=crop&w=1920&q=80');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    display: flex;
    align-items: center;
    color: white;
    position: relative;
}
.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 20px;
    text-transform: uppercase;
    letter-spacing: 1px;
}
.hero-content p {
    font-size: 1.2rem;
    margin-bottom: 30px;
    opacity: 0.9;
}

/* --- SECTION GENERAL --- */
.section-padding {
    padding: 80px 0;
}
.section-title {
    text-align: center;
    margin-bottom: 60px;
}
.section-title h2 {
    color: var(--primary-color);
    position: relative;
    display: inline-block;
    margin-bottom: 15px;
}
.section-title h2::after {
    content: '';
    display: block;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
    margin: 10px auto 0;
}
.section-title p {
    color: var(--text-gray);
    max-width: 600px;
    margin: 0 auto;
}

/* --- STATS --- */
.stats-section {
    background-color: var(--accent-color);
    color: white;
    padding: 40px 0;
    margin-top: -60px;
    position: relative;
    z-index: 10;
}
.stat-item h3 { font-size: 2.5rem; margin-bottom: 0; }
.stat-item p { font-size: 1rem; margin-bottom: 0; opacity: 0.9; }

/* --- ABOUT --- */
.about-img {
    border-radius: 8px;
    box-shadow: 0 15px 30px rgba(0,0,0,0.1);
    width: 100%;
    height: 400px;
    object-fit: cover;
}

/* --- SERVICES / INFRASTRUCTURE --- */
.service-card {
    background: white;
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    transition: 0.3s;
    height: 100%;
    border-bottom: 3px solid transparent;
}
.service-card:hover {
    transform: translateY(-10px);
    border-bottom: 3px solid var(--accent-color);
}
.service-icon {
    font-size: 40px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

/* --- GALLERY --- */
.gallery-item {
    position: relative;
    overflow: hidden;
    border-radius: 8px;
    cursor: pointer;
    margin-bottom: 24px;
}
.gallery-item img {
    width: 100%;
    height: 300px;
    object-fit: cover;
    transition: 0.5s;
}
.gallery-overlay {
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(13, 37, 63, 0.8);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    opacity: 0;
    transition: 0.4s;
    color: white;
}
.gallery-item:hover img { transform: scale(1.1); }
.gallery-item:hover .gallery-overlay { opacity: 1; }

/* --- CONTACT --- */
.contact-section {
    background-color: var(--light-bg);
}
.contact-form {
    background: white;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
}
.form-control {
    padding: 12px;
    border-radius: 5px;
    margin-bottom: 20px;
    border: 1px solid #ddd;
}
.form-control:focus {
    box-shadow: none;
    border-color: var(--accent-color);
}
.btn-submit {
    background-color: var(--primary-color);
    color: white;
    width: 100%;
    padding: 12px;
    font-weight: bold;
    text-transform: uppercase;
    border: none;
    transition: 0.3s;
}
.btn-submit:hover {
    background-color: var(--accent-color);
}

/* --- FOOTER --- */
footer {
    background-color: var(--primary-color);
    color: white;
    padding: 50px 0 20px;
}
footer h5 { color: var(--accent-color); margin-bottom: 20px; }
footer ul { list-style: none; padding: 0; }
footer ul li { margin-bottom: 10px; }
footer a { color: rgba(255,255,255,0.7); text-decoration: none; }
footer a:hover { color: white; }
.social-icons a {
    color: white;
    margin-right: 15px;
    font-size: 18px;
}
.copyright {
    border-top: 1px solid rgba(255,255,255,0.1);
    margin-top: 40px;
    padding-top: 20px;
    text-align: center;
    font-size: 14px;
    color: rgba(255,255,255,0.5);
}