/* 
   CSS cho Landing Page Thiết kế Thi công trọn gói An Nam
   Phong cách: Sang trọng, đẳng cấp (Dark Gold Theme)
   Tất cả các comment được dịch/ghi chú bằng tiếng Việt để dễ quản lý.
*/

/* 1. KHỞI TẠO HỆ THỐNG BIẾN MÀU VÀ FONTS */
@import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@300;400;500;600;700&family=Playfair+Display:ital,wght@0,400;0,600;0,700;1,400&display=swap');

:root {
    /* Tông màu chủ đạo */
    --primary: #c5a880; /* Màu vàng đồng (Gold) sang trọng */
    --primary-hover: #dfb98a; /* Vàng đồng sáng khi hover */
    --bg-dark: #0b0b0b; /* Màu đen nền sâu thẳm */
    --bg-card: #151515; /* Màu đen nền cho các thẻ dịch vụ, dự án */
    --bg-card-hover: #1e1e1e; /* Màu thẻ khi di chuột qua */
    --text-light: #ffffff; /* Chữ màu trắng */
    --text-muted: #a0a0a0; /* Chữ màu xám mờ cho nội dung phụ */
    --text-dark: #111111; /* Chữ màu tối cho nền sáng */
    --border-color: rgba(197, 168, 128, 0.15); /* Viền gold mờ */
    --border-hover: rgba(197, 168, 128, 0.4); /* Viền gold rõ hơn khi hover */
    --accent: #e5c090; /* Màu nhấn phụ sáng hơn */
    
    /* Font chữ */
    --font-heading: 'Playfair Display', serif; /* Font chữ tiêu đề cổ điển, sang trọng */
    --font-body: 'Montserrat', sans-serif; /* Font chữ nội dung hiện đại, dễ nhìn */
    
    /* Cấu hình hiệu ứng */
    --transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
    --shadow-gold: 0 10px 30px rgba(197, 168, 128, 0.1);
}

/* 2. THIẾT LẬP CƠ BẢN (RESET & BASE STYLES) */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
    background-color: var(--bg-dark);
    color: var(--text-light);
    font-family: var(--font-body);
    -webkit-font-smoothing: antialiased;
}

body {
    overflow-x: hidden;
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

button, input, textarea {
    font-family: inherit;
    background: none;
    border: none;
    outline: none;
}

/* CONTAINER */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* NÚT BẤM (BUTTONS) */
.btn {
    display: inline-block;
    padding: 14px 32px;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 2px;
    border-radius: 0; /* Bo góc vuông vức tạo nét cổ điển sang trọng */
    cursor: pointer;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    z-index: 1;
}

.btn-primary {
    background-color: var(--primary);
    color: var(--bg-dark);
    border: 1px solid var(--primary);
}

.btn-primary:hover {
    background-color: transparent;
    color: var(--primary);
    box-shadow: var(--shadow-gold);
}

.btn-outline {
    background-color: transparent;
    color: var(--primary);
    border: 1px solid var(--border-color);
}

.btn-outline:hover {
    border-color: var(--primary);
    background-color: rgba(197, 168, 128, 0.05);
}

/* TIÊU ĐỀ SECTION (SECTION HEADERS) */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-subtitle {
    font-size: 0.85rem;
    text-transform: uppercase;
    color: var(--primary);
    letter-spacing: 4px;
    font-weight: 600;
    margin-bottom: 12px;
    display: inline-block;
}

.section-title {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1.3;
    color: var(--text-light);
    position: relative;
    padding-bottom: 15px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 2px;
    background-color: var(--primary);
}

/* 3. HEADER & MENU NAVIGATION */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1000;
    transition: var(--transition);
    border-bottom: 1px solid rgba(255, 255, 255, 0.03);
}

header.scrolled {
    background-color: rgba(11, 11, 11, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 5px 20px rgba(0, 0, 0, 0.3);
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    transition: var(--transition);
}

header.scrolled .header-container {
    padding: 10px 0;
}

.logo img {
    height: 50px;
    width: auto;
    transition: var(--transition);
}

header.scrolled .logo img {
    height: 40px;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-link {
    font-size: 0.85rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-muted);
}

.nav-link:hover, .nav-link.active {
    color: var(--primary);
}

.header-cta {
    display: flex;
    align-items: center;
    gap: 20px;
}

.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    cursor: pointer;
    z-index: 1001;
}

.menu-toggle span {
    width: 25px;
    height: 2px;
    background-color: var(--text-light);
    transition: var(--transition);
}

/* 4. HERO SECTION */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    padding-top: 100px;
    background: radial-gradient(circle at center, rgba(197, 168, 128, 0.08) 0%, rgba(11, 11, 11, 1) 70%);
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(0deg, var(--bg-dark) 0%, rgba(11, 11, 11, 0.4) 50%, rgba(11, 11, 11, 0.8) 100%);
    z-index: 1;
}

.hero-bg-carousel {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    opacity: 0.45;
}

.hero-bg-slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-size: cover;
    background-position: center;
    opacity: 0;
    transition: opacity 1.5s ease-in-out, transform 8s ease;
    transform: scale(1.05);
}

.hero-bg-slide.active {
    opacity: 1;
    transform: scale(1);
}

.hero .container {
    position: relative;
    z-index: 2;
}

.hero-content {
    max-width: 750px;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background-color: rgba(197, 168, 128, 0.1);
    border: 1px solid var(--border-color);
    padding: 8px 16px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--primary);
    margin-bottom: 24px;
}

.hero-title {
    font-family: var(--font-heading);
    font-size: 3.8rem;
    line-height: 1.15;
    font-weight: 700;
    margin-bottom: 24px;
    color: var(--text-light);
}

.hero-title span {
    color: var(--primary);
    display: block;
}

.hero-desc {
    font-size: 1.1rem;
    color: var(--text-muted);
    margin-bottom: 40px;
    font-weight: 300;
    max-width: 600px;
}

.hero-actions {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

/* 5. STATS SECTION */
.stats {
    padding: 60px 0;
    background-color: #0d0d0d;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    position: relative;
    z-index: 10;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 30px;
    text-align: center;
}

.stat-item {
    padding: 20px;
    position: relative;
}

.stat-item:not(:last-child)::after {
    content: '';
    position: absolute;
    right: -15px;
    top: 25%;
    width: 1px;
    height: 50%;
    background-color: var(--border-color);
}

.stat-number {
    font-family: var(--font-heading);
    font-size: 3.5rem;
    font-weight: 700;
    color: var(--primary);
    line-height: 1;
    margin-bottom: 10px;
}

.stat-title {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--text-muted);
    font-weight: 600;
}

/* 6. SERVICES SECTION */
.services {
    padding: 120px 0;
    background-color: var(--bg-dark);
}

.services-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 30px;
}

.service-card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 50px 40px;
    transition: var(--transition);
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    height: 100%;
}

.service-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--primary);
    transform: scaleX(0);
    transform-origin: left;
    transition: var(--transition);
}

.service-card:hover {
    transform: translateY(-8px);
    border-color: var(--border-hover);
    background-color: var(--bg-card-hover);
    box-shadow: var(--shadow);
}

.service-card:hover::before {
    transform: scaleX(1);
}

.service-icon {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: 30px;
    display: inline-block;
}

.service-card h3 {
    font-family: var(--font-heading);
    font-size: 1.5rem;
    margin-bottom: 16px;
    color: var(--text-light);
}

.service-card p {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 30px;
    line-height: 1.7;
}

.service-more {
    font-size: 0.8rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--primary);
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.service-more i {
    font-size: 0.75rem;
    transition: var(--transition);
}

.service-card:hover .service-more i {
    transform: translateX(5px);
}

/* 7. PORTFOLIO SECTION */
.portfolio {
    padding: 120px 0;
    background-color: #0d0d0d;
}

.portfolio-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
    margin-bottom: 50px;
}

.portfolio-item {
    position: relative;
    overflow: hidden;
    aspect-ratio: 4/3;
    border: 1px solid var(--border-color);
}

.portfolio-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 1.2s cubic-bezier(0.16, 1, 0.3, 1);
}

.portfolio-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to top, rgba(11, 11, 11, 0.95) 0%, rgba(11, 11, 11, 0.4) 60%, transparent 100%);
    opacity: 0;
    transition: var(--transition);
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    padding: 40px;
    z-index: 2;
}

.portfolio-info {
    transform: translateY(20px);
    transition: var(--transition);
}

.portfolio-category {
    font-size: 0.8rem;
    color: var(--primary);
    text-transform: uppercase;
    letter-spacing: 2px;
    margin-bottom: 8px;
    font-weight: 600;
}

.portfolio-title {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    color: var(--text-light);
    margin-bottom: 12px;
}

.portfolio-link {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    font-weight: 500;
    color: var(--primary);
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border-bottom: 1px solid transparent;
}

.portfolio-link:hover {
    border-color: var(--primary);
}

.portfolio-item:hover .portfolio-img {
    transform: scale(1.08);
}

.portfolio-item:hover .portfolio-overlay {
    opacity: 1;
}

.portfolio-item:hover .portfolio-info {
    transform: translateY(0);
}

.portfolio-action {
    text-align: center;
}

/* 8. PROCESS SECTION */
.process {
    padding: 120px 0;
    background-color: var(--bg-dark);
}

.process-content {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 60px;
    align-items: center;
}

.process-steps {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.process-step {
    display: flex;
    gap: 24px;
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 24px;
    transition: var(--transition);
}

.process-step:hover {
    border-color: var(--border-hover);
    background-color: var(--bg-card-hover);
}

.step-num {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    color: var(--primary);
    font-weight: 700;
    line-height: 1;
}

.step-info h4 {
    font-size: 1.1rem;
    margin-bottom: 8px;
    color: var(--text-light);
    font-weight: 600;
}

.step-info p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

.process-img-wrapper {
    position: relative;
    border: 1px solid var(--border-color);
    padding: 10px;
    background-color: #0d0d0d;
}

.process-img-wrapper img {
    width: 100%;
    height: auto;
    object-fit: cover;
    filter: grayscale(30%);
    transition: var(--transition);
}

.process-img-wrapper:hover img {
    filter: grayscale(0%);
}

/* 9. ABOUT & TEAM SECTION */
.about {
    padding: 120px 0;
    background-color: #0d0d0d;
}

.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-img-box {
    position: relative;
}

.about-img {
    border: 1px solid var(--border-color);
    padding: 10px;
    background-color: var(--bg-card);
}

.about-img img {
    width: 100%;
    height: auto;
    object-fit: cover;
}

.about-experience {
    position: absolute;
    bottom: -20px;
    right: -20px;
    background-color: var(--primary);
    color: var(--bg-dark);
    padding: 30px;
    text-align: center;
    border: 5px solid var(--bg-dark);
    max-width: 180px;
    box-shadow: var(--shadow);
}

.about-exp-num {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    font-weight: 700;
    line-height: 1;
    margin-bottom: 5px;
}

.about-exp-text {
    font-size: 0.75rem;
    text-transform: uppercase;
    font-weight: 700;
    letter-spacing: 1px;
}

.about-content h3 {
    font-family: var(--font-heading);
    font-size: 2.2rem;
    line-height: 1.3;
    margin-bottom: 24px;
}

.about-content p {
    color: var(--text-muted);
    margin-bottom: 30px;
    font-size: 1rem;
    line-height: 1.8;
}

.about-videos {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 35px;
}

.video-thumb-card {
    position: relative;
    cursor: pointer;
    overflow: hidden;
    border: 1px solid var(--border-color);
    aspect-ratio: 16/9;
    background-color: var(--bg-dark);
}

.video-thumb-img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0.65;
    transition: var(--transition);
}

.video-play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 50px;
    height: 50px;
    background-color: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--bg-dark);
    font-size: 1.2rem;
    transition: var(--transition);
    z-index: 2;
    box-shadow: 0 0 20px rgba(197, 168, 128, 0.4);
}

.video-play-btn i {
    margin-left: 3px;
}

.video-title-card {
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    padding: 10px 15px;
    background: linear-gradient(to top, rgba(0, 0, 0, 0.8), transparent);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-light);
    z-index: 3;
}

.video-thumb-card:hover .video-thumb-img {
    transform: scale(1.05);
    opacity: 0.85;
}

.video-thumb-card:hover .video-play-btn {
    background-color: var(--text-light);
    box-shadow: 0 0 25px rgba(255, 255, 255, 0.6);
    transform: translate(-50%, -50%) scale(1.1);
}

/* 10. CLIENTS TRUST SECTION */
.clients {
    padding: 60px 0;
    background-color: #0b0b0b;
    border-top: 1px solid var(--border-color);
}

.clients-list {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    align-items: center;
    gap: 40px;
}

.client-logo {
    font-family: var(--font-heading);
    font-size: 1.1rem;
    color: var(--text-muted);
    font-weight: 600;
    letter-spacing: 2px;
    padding: 10px 20px;
    border: 1px solid transparent;
    transition: var(--transition);
}

.client-logo:hover {
    color: var(--primary);
    border-color: var(--border-color);
    background-color: var(--bg-card);
}

/* 11. CONTACT SECTION */
.contact {
    padding: 120px 0;
    background-color: var(--bg-dark);
}

.contact-grid {
    display: grid;
    grid-template-columns: 0.9fr 1.1fr;
    gap: 60px;
}

.contact-info-box {
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.contact-info-desc {
    color: var(--text-muted);
    font-size: 1rem;
    line-height: 1.7;
}

.info-item {
    display: flex;
    gap: 20px;
    align-items: flex-start;
}

.info-icon {
    font-size: 1.3rem;
    color: var(--primary);
    margin-top: 3px;
}

.info-text h5 {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--primary);
    margin-bottom: 6px;
}

.info-text p {
    color: var(--text-light);
    font-size: 1rem;
}

.info-text a:hover {
    color: var(--primary);
}

.contact-form-box {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 50px 40px;
}

.form-group {
    margin-bottom: 24px;
}

.form-control {
    width: 100%;
    background-color: rgba(255, 255, 255, 0.02);
    border: 1px solid var(--border-color);
    padding: 16px 20px;
    color: var(--text-light);
    font-size: 0.95rem;
    transition: var(--transition);
}

.form-control:focus {
    border-color: var(--primary);
    background-color: rgba(255, 255, 255, 0.04);
}

textarea.form-control {
    resize: none;
    height: 120px;
}

.form-control::placeholder {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.contact-form-box h4 {
    font-family: var(--font-heading);
    font-size: 1.8rem;
    margin-bottom: 12px;
    color: var(--text-light);
}

.contact-form-box p {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 30px;
}

/* 12. FOOTER */
footer {
    background-color: #070707;
    padding: 80px 0 40px;
    border-top: 1px solid var(--border-color);
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr 1fr 1fr;
    gap: 50px;
    margin-bottom: 60px;
}

.footer-about .logo-footer {
    height: 60px;
    margin-bottom: 20px;
}

.footer-about p {
    color: var(--text-muted);
    font-size: 0.9rem;
    line-height: 1.7;
    margin-bottom: 24px;
}

.social-links {
    display: flex;
    gap: 16px;
}

.social-link {
    width: 40px;
    height: 40px;
    border: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-muted);
}

.social-link:hover {
    color: var(--bg-dark);
    background-color: var(--primary);
    border-color: var(--primary);
}

.footer-links h4 {
    font-family: var(--font-heading);
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 24px;
    position: relative;
    padding-bottom: 10px;
}

.footer-links h4::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 30px;
    height: 1.5px;
    background-color: var(--primary);
}

.footer-links ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.footer-links ul a {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.footer-links ul a:hover {
    color: var(--primary);
    padding-left: 6px;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.05);
    padding-top: 40px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 20px;
}

.copyright {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer-policy {
    display: flex;
    gap: 24px;
}

.footer-policy a {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer-policy a:hover {
    color: var(--primary);
}

/* 12.1 VIDEO GALLERY */
.video-gallery {
    padding: 100px 0;
    background-color: var(--bg-dark);
    border-top: 1px solid var(--border-color);
    position: relative;
    z-index: 10;
}

.video-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.video-wrapper {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    padding: 15px;
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.video-wrapper:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-gold);
    transform: translateY(-5px);
}

.video-responsive {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 56.25%; /* Tỷ lệ 16:9 */
    overflow: hidden;
}

.video-responsive iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border: none;
}

.video-desc-box {
    margin-top: 20px;
    text-align: center;
}

.video-desc-box h4 {
    font-family: var(--font-heading);
    font-size: 1.3rem;
    color: var(--primary);
    margin-bottom: 8px;
}

.video-desc-box p {
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* 13. VIDEO MODAL POPUP */
.video-modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(7, 7, 7, 0.98);
    backdrop-filter: blur(15px);
    z-index: 2000;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.5s ease;
}

.video-modal.active {
    opacity: 1;
    pointer-events: auto;
}

.video-modal-content {
    position: relative;
    width: 90%;
    max-width: 900px;
    aspect-ratio: 16/9;
    border: 1px solid var(--border-color);
    background-color: #000;
}

.video-modal-content iframe {
    width: 100%;
    height: 100%;
    border: none;
}

.video-modal-close {
    position: absolute;
    top: -50px;
    right: 0;
    color: var(--text-light);
    font-size: 2rem;
    cursor: pointer;
    transition: var(--transition);
}

.video-modal-close:hover {
    color: var(--primary);
    transform: rotate(90deg);
}

/* 14. ANIMATIONS & SCROLL REVEAL CLASSIFICATION */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

.reveal-delay-1 { transition-delay: 0.15s; }
.reveal-delay-2 { transition-delay: 0.3s; }
.reveal-delay-3 { transition-delay: 0.45s; }

/* 15. RESPONSIVE DESIGN */
@media (max-width: 1024px) {
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 40px;
    }
    
    .stat-item:nth-child(2)::after {
        display: none;
    }
    
    .services-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .services-grid .service-card:last-child {
        grid-column: span 2;
    }
    
    .about-grid, .process-content, .contact-grid {
        grid-template-columns: 1fr;
        gap: 50px;
    }
    
    .process-content {
        display: flex;
        flex-direction: column-reverse;
    }
    
    .video-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }
}

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }
    
    .hero-title {
        font-size: 2.8rem;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    /* Responsive Menu di động */
    .menu-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 400px;
        height: 100vh;
        background-color: #0d0d0d;
        border-left: 1px solid var(--border-color);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 40px;
        z-index: 1000;
        transition: var(--transition);
    }
    
    .nav-menu.active {
        right: 0;
    }
    
    .menu-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(6px, 6px);
    }
    
    .menu-toggle.active span:nth-child(2) {
        opacity: 0;
    }
    
    .menu-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    
    .header-cta .btn {
        display: none; /* Ẩn nút CTA header trên mobile */
    }
    
    .portfolio-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 40px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2.3rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .stat-item::after {
        display: none !important;
    }
    
    .services-grid {
        grid-template-columns: 1fr;
    }
    
    .services-grid .service-card:last-child {
        grid-column: span 1;
    }
    
    .about-videos {
        grid-template-columns: 1fr;
    }
    
    .about-experience {
        position: static;
        margin: 20px auto 0;
        max-width: 100%;
    }
}