* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary: #f5f5f5;          /* nền sáng, dịu mắt nhưng vẫn nam tính */
    --secondary: #e0e0e0;        /* nền phụ sáng hơn một chút */
    --accent: #ff1f1f;           /* đỏ rực, mạnh mẽ */
    --accent-light: #ff4d4d;     /* đỏ sáng cho hover/nút */
    --text-primary: #1a1a1a;     /* chữ tối, nổi bật trên nền sáng */
    --text-secondary: #555555;   /* chữ phụ, nhìn chuyên nghiệp */
    --border: #cc0000;           /* viền đỏ đậm, nam tính */
}



body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--primary);
    color: var(--text-primary);
    line-height: 1.6;
}

/* Header & Navigation */
header {
    background-color: var(--secondary);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.5rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.nav-links a:hover {
    color: var(--accent);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    padding: 6rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border);
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    line-height: 1.2;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
}

.btn {
    padding: 0.75rem 2rem;
    border: none;
    border-radius: 50px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background-color: var(--accent);
    color: white;
}

.btn-primary:hover {
    background-color: var(--accent-light);
    transform: translateY(-2px);
}

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

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Warning Section - Nghiêm trọng */
.warning {
    background-color: #f9f5f5;       /* nền sáng trung tính, nhìn sạch và nghiêm túc */
    padding: 4rem 2rem;
    border-bottom: 1px solid #b30000; /* viền đỏ trầm */
}

.warning-content {
    max-width: 1000px;
    margin: 0 auto;
}

.warning h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #b30000;                  /* đỏ trầm nghiêm túc */
}

.warning-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.warning-card {
    background-color: #ffffff;       /* nền card trắng nổi bật */
    padding: 2rem;
    border: 1px solid #990000;       /* viền đỏ trầm */
    border-radius: 8px;
    transition: all 0.3s ease;
}

.warning-card:hover {
    border-color: #ff1f1f;           /* đỏ sáng khi hover */
    transform: translateY(-4px);
}

.warning-card h3 {
    color: #b30000;                  /* header card đỏ trầm */
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.warning-card p {
    color: #333333;                  /* chữ phụ tối nghiêm túc */
    line-height: 1.8;
}

/* Steps Section */
.steps {
    padding: 4rem 2rem;
    background-color: var(--primary);
    border-bottom: 1px solid var(--border);
}

.steps-content {
    max-width: 1200px;
    margin: 0 auto;
}

.steps h2 {
    font-size: 2rem;
    margin-bottom: 3rem;
    text-align: center;
}

.steps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.step-card {
    background-color: var(--secondary);
    padding: 2rem;
    border-radius: 8px;
    border: 1px solid var(--border);
    transition: all 0.3s ease;
    position: relative;
}

.step-card:hover {
    border-color: var(--accent);
    box-shadow: 0 8px 24px rgba(255, 107, 53, 0.1);
}

.step-number {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background-color: var(--accent);
    color: white;
    border-radius: 50%;
    font-weight: 700;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.step-card h3 {
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.step-card p {
    color: var(--text-secondary);
    line-height: 1.8;
}
.reviews {
    background: #f8f9fa;
    padding: 80px 20px;
    text-align: center;
}

.reviews-content h2 {
    font-size: 2.4em;
    margin-bottom: 15px;
    font-weight: 700;
    color: #222;
}

.reviews-content .subtitle {
    color: #555;
    font-size: 1.1em;
    margin-bottom: 40px;
}

.reviews-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px; /* khoảng cách đồng đều cả ngang lẫn dọc */
    justify-items: center;
    align-items: center;
    padding: 20px 0;
}

.reviews-gallery img {
    width: 100%;           /* chiếm toàn bộ khung cột */
    height: auto;          /* giữ tỉ lệ gốc */
    max-width: 100%;       /* tránh bị tràn */
    object-fit: contain;   /* hiển thị toàn bộ ảnh, không bị cắt */
    border-radius: 8px;
    box-shadow: 0 6px 15px rgba(0,0,0,0.2);
    cursor: pointer;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.reviews-gallery img:hover {
    transform: scale(1.05);
    box-shadow: 0 8px 20px rgba(0,0,0,0.3);
}


/* Lightbox */
#lightbox {
    display: none; /* Ẩn khi load trang */
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    justify-content: center;
    align-items: center;
    background: rgba(0,0,0,0.8);
    z-index: 9999;
}

#lightbox img {
    max-width: 90%;
    max-height: 90%;
    border-radius: 10px;
}

.close, .prev, .next {
    position: absolute;
    color: white;
    font-size: 50px;
    font-weight: bold;
    cursor: pointer;
    user-select: none;
}

.close { top: 20px; right: 30px; }
.prev { top: 50%; left: 20px; transform: translateY(-50%); }
.next { top: 50%; right: 20px; transform: translateY(-50%); }

.close:hover, .prev:hover, .next:hover {
    color: #ccc;
}


.contact {
    background: linear-gradient(135deg, var(--secondary) 0%, var(--primary) 100%);
    padding: 4rem 2rem;
    border-bottom: 1px solid var(--border);
}

.contact-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.contact h2 {
    font-size: 2rem;
    margin-bottom: 1.5rem;
}

.contact p {
    color: var(--text-secondary);
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

.contact-form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    text-align: left;
}

.form-group label {
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    padding: 0.75rem;
    border: 1px solid var(--border);
    background-color: var(--primary);
    color: var(--text-primary);
    border-radius: 4px;
    font-family: inherit;
    transition: border-color 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* Footer */
footer {
    background-color: var(--secondary);
    border-top: 1px solid var(--border);
    padding: 3rem 2rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h3 {
    margin-bottom: 1rem;
    color: var(--accent);
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-section a:hover {
    color: var(--accent);
}

.footer-bottom {
    border-top: 1px solid var(--border);
    padding-top: 2rem;
    text-align: center;
    color: var(--text-secondary);
}

/* Responsive */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 2rem;
    }

    .nav-links {
        gap: 1rem;
        font-size: 0.9rem;
    }

    .cta-buttons {
        flex-direction: column;
    }

    .btn {
        width: 100%;
    }
}