:root {
    --c-primary: #0f4c81;     /* Classic Corporate Blue */
    --c-secondary: #059669;   /* Trustworthy Emerald Green */
    --c-light: #f8fafc;       /* Slate 50 - Background */
    --c-dark: #0f172a;        /* Slate 900 - Headings */
    --c-gray: #e2e8f0;        /* Slate 200 - Borders */
    --c-gray-text: #64748b;   /* Slate 500 - Body Text */
    --bg-white: #ffffff;
    --font-main: 'Inter', sans-serif;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { font-family: var(--font-main); background-color: var(--c-light); color: var(--c-gray-text); line-height: 1.7; overflow-x: hidden; }

a { text-decoration: none; color: inherit; transition: var(--transition); }
img { max-width: 100%; height: auto; display: block; }
ul { list-style: none; }

.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.section { padding: 100px 0; }
.bg-light { background-color: var(--bg-white); }
.bg-corporate { background-color: var(--c-primary); color: white; }
.center { text-align: center; }

/* Grid Utilities */
.grid-50-50 { display: grid; grid-template-columns: 1fr 1fr; gap: 60px; align-items: center; }
.grid-3-cols { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.grid-4-cols { display: grid; grid-template-columns: repeat(4, 1fr); gap: 30px; }

/* Typography */
h1, h2, h3, h4, h5, h6 { color: var(--c-dark); font-weight: 700; line-height: 1.2; }
.bg-corporate h1, .bg-corporate h2, .bg-corporate h3 { color: white; }
.overline { color: var(--c-secondary); font-size: 0.85rem; font-weight: 700; text-transform: uppercase; letter-spacing: 2px; margin-bottom: 10px; display: inline-block; }
.section-title { font-size: 2.5rem; margin-bottom: 20px; letter-spacing: -0.5px; }
.subtitle { font-size: 1.1rem; color: var(--c-gray-text); max-width: 600px; margin: 0 auto 50px; }

/* Buttons */
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 12px 24px; border-radius: 4px; font-weight: 600; font-size: 1rem; cursor: pointer; border: none; transition: var(--transition); }
.btn-primary { background-color: var(--c-secondary); color: white; }
.btn-primary:hover { background-color: #047857; transform: translateY(-2px); box-shadow: var(--shadow-md); color: white;}
.btn-secondary { background-color: white; color: var(--c-primary); border: 1px solid var(--c-gray); }
.btn-secondary:hover { background-color: var(--c-light); }
.btn-outline { background-color: transparent; border: 2px solid var(--c-primary); color: var(--c-primary); }
.btn-outline:hover { background-color: var(--c-primary); color: white; }
.navbar .btn-outline { border-color: white; color: white; }
.navbar.scrolled .btn-outline { border-color: var(--c-primary); color: var(--c-primary); }
.navbar.scrolled .btn-outline:hover { background: var(--c-primary); color: white; }
.btn-lg { padding: 16px 36px; font-size: 1.1rem; }
.btn-full { width: 100%; display: block; }

/* Animations */
.fade-in { opacity: 0; transform: translateY(30px); transition: 0.8s ease; }
.fade-in-up { opacity: 0; transform: translateY(40px); transition: 0.8s ease; }
.visible { opacity: 1; transform: translateY(0); }
.delay-1 { transition-delay: 0.2s; }
.delay-2 { transition-delay: 0.4s; }

/* Navbar */
.navbar { position: fixed; top: 0; left: 0; width: 100%; padding: 25px 0; z-index: 1000; transition: var(--transition); border-bottom: 1px solid rgba(255,255,255,0.1); }
.navbar.scrolled { padding: 15px 0; background-color: rgba(255,255,255,0.98); backdrop-filter: blur(10px); box-shadow: var(--shadow-sm); border-bottom: 1px solid var(--c-gray); }
.nav-container { display: flex; justify-content: space-between; align-items: center; }
.brand { display: flex; align-items: center; gap: 10px; font-size: 1.6rem; font-weight: 800; color: white; letter-spacing: -0.5px; }
.brand-icon { color: var(--c-secondary); }
.navbar.scrolled .brand { color: var(--c-primary); }
.nav-links { display: flex; gap: 30px; align-items: center; }
.nav-link { color: rgba(255,255,255,0.9); font-weight: 500; }
.nav-link:hover { color: white; }
.navbar.scrolled .nav-link { color: var(--c-dark); }
.navbar.scrolled .nav-link:hover { color: var(--c-secondary); }
.nav-actions { display: flex; align-items: center; gap: 15px; }

.lang-toggle { font-weight: 600; color: rgba(255,255,255,0.6); font-size: 0.95rem; }
.lang-toggle.active { color: white; }
.navbar.scrolled .lang-toggle { color: var(--c-gray-text); }
.navbar.scrolled .lang-toggle.active { color: var(--c-primary); }

/* Hero Section */
.hero { position: relative; height: 100vh; display: flex; align-items: center; justify-content: center; }
.hero-bg { position: absolute; top: 0; left: 0; width: 100%; height: 100%; object-fit: cover; z-index: -2; }
.hero-overlay { position: absolute; top: 0; left: 0; width: 100%; height: 100%; background: linear-gradient(90deg, rgba(15,23,42,0.8) 0%, rgba(15,23,42,0.4) 100%); z-index: -1; }
.hero-content { position: relative; z-index: 1; text-align: center; color: white; max-width: 900px; padding: 0 20px;}
.hero-title { font-size: 4.5rem; color: white; line-height: 1.1; margin-bottom: 20px; }
.hero-subtitle { font-size: 1.25rem; color: rgba(255,255,255,0.9); margin-bottom: 40px; font-weight: 300; }
.hero-buttons { display: flex; gap: 20px; justify-content: center; }

/* Bottom Stats */
.hero-bottom-stats { position: absolute; bottom: 0; left: 50%; transform: translate(-50%, 50%); width: 100%; max-width: 1000px; display: grid; grid-template-columns: repeat(3, 1fr); background: white; border-radius: 8px; box-shadow: var(--shadow-lg); z-index: 10; overflow: hidden; }
.stat-box { padding: 40px 20px; text-align: center; border-right: 1px solid var(--c-gray); }
.stat-box:last-child { border-right: none; }
.stat-num { font-size: 3rem; font-weight: 800; color: var(--c-primary); line-height: 1; }
.stat-unit { font-size: 1.5rem; font-weight: 700; color: var(--c-primary); margin-left: 5px; }
.stat-label { display: block; color: var(--c-gray-text); font-weight: 500; font-size: 0.95rem; text-transform: uppercase; letter-spacing: 1px; margin-top: 5px; }

/* About Section */
.about-section { padding-top: 150px; } /* Spacer for overlay stats */
.experience-badge { position: absolute; bottom: 30px; left: -30px; background: var(--c-primary); color: white; padding: 25px; border-radius: 8px; display: flex; align-items: center; gap: 15px; box-shadow: var(--shadow-lg); }
.experience-badge .yr { font-size: 3rem; font-weight: 800; line-height: 1; color: var(--c-secondary); }
.experience-badge span { font-weight: 600; line-height: 1.2; text-transform: uppercase; font-size: 0.9rem; }
.feature-img { border-radius: 8px; box-shadow: var(--shadow-md); }
.checklist { margin-top: 30px; }
.checklist li { display: flex; align-items: flex-start; gap: 15px; margin-bottom: 15px; color: var(--c-dark); font-weight: 500; }
.checklist i { color: var(--c-secondary); padding: 5px; background: rgba(5, 150, 105, 0.1); border-radius: 50%; font-size: 0.8rem; margin-top: 3px; }

/* Services Grid (Detailed Cards) */
.service-card { background: white; border-radius: 8px; border: 1px solid var(--c-gray); overflow: hidden; transition: var(--transition); }
.service-card:hover { transform: translateY(-5px); box-shadow: var(--shadow-md); border-color: var(--c-primary); }
.card-img { height: 220px; overflow: hidden; }
.card-img img { width: 100%; height: 100%; object-fit: cover; transition: 0.5s ease; }
.service-card:hover .card-img img { transform: scale(1.05); }
.card-body { padding: 30px; }
.card-body h3 { font-size: 1.4rem; margin-bottom: 15px; }
.card-body p { margin-bottom: 25px; }

/* Advantages Grid */
.adv-item { padding: 40px 30px; text-align: center; border-radius: 8px; background: var(--c-light); border: 1px solid var(--c-gray); transition: var(--transition); }
.adv-item:hover { background: white; box-shadow: var(--shadow-md); }
.adv-icon { font-size: 2.5rem; color: var(--c-secondary); margin-bottom: 20px; }
.adv-item h3 { margin-bottom: 10px; font-size: 1.25rem; }

/* Partners Logos */
.partner-logos { display:flex; justify-content:center; align-items:center; flex-wrap:wrap; gap: 40px; margin-top: 50px;}
.partner-logo { padding: 20px; text-align:center; min-width: 180px; transition: var(--transition); opacity: 0.6; filter: grayscale(100%); }
.partner-logo:hover { opacity: 1; filter: grayscale(0%); transform: translateY(-5px); }
.partner-logo img { max-width: 160px; max-height: 55px; object-fit: contain; margin: 0 auto;}

/* Contact Section */
.corporate-form { background: white; padding: 40px; border-radius: 8px; box-shadow: var(--shadow-lg); color: var(--c-dark); }
.corporate-form h3 { font-size: 1.6rem; margin-bottom: 25px; }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; font-weight: 600; margin-bottom: 8px; font-size: 0.95rem; }
.form-input { width: 100%; padding: 14px 15px; border: 1px solid var(--c-gray); border-radius: 4px; font-family: var(--font-main); font-size: 1rem; transition: var(--transition); }
.form-input:focus { outline: none; border-color: var(--c-primary); box-shadow: 0 0 0 3px rgba(15, 76, 129, 0.1); }
.contact-info-block { padding-right: 40px; }
.c-item { display: flex; gap: 20px; margin-bottom: 30px; }
.c-item i { font-size: 1.5rem; color: var(--c-secondary); background: rgba(255,255,255,0.1); width: 60px; height: 60px; display: flex; align-items: center; justify-content: center; border-radius: 50%; }
.c-item span { display: block; font-size: 0.9rem; color: rgba(255,255,255,0.7); margin-bottom: 5px; }
.c-item strong { display: block; font-size: 1.2rem; font-weight: 700; color: white; }

.msg-box { display: none; padding: 15px; margin-top: 15px; border-radius: 4px; font-weight: 600; text-align: center; }
.msg-box.success { display: block; background: #def7ec; color: #03543f; border: 1px solid #84e1bc; }

/* Footer */
.footer { background-color: var(--c-dark); color: rgba(255,255,255,0.7); padding-top: 80px; }
.footer h4 { color: white; margin-bottom: 25px; font-size: 1.2rem; }
.footer-links li { margin-bottom: 12px; }
.footer-links a:hover { color: var(--c-secondary); padding-left: 5px; }
.border-top { border-top: 1px solid rgba(255,255,255,0.1); padding: 25px 0; margin-top: 60px; font-size: 0.9rem; }

/* Mobile nav */
.mobile-toggle { display: none; background: transparent; border: none; color: white; font-size: 1.8rem; cursor: pointer; }
@media(max-width: 900px) {
    .grid-50-50, .grid-3-cols, .grid-4-cols { grid-template-columns: 1fr; }
    .d-none-sm { display: none !important; }
    .d-none-sm { display: none !important; }
    
    .nav-links { position: fixed; top: 70px; left: -100%; width: 100%; background: white; flex-direction: column; align-items: center; padding: 20px 0; transition: 0.3s; box-shadow: var(--shadow-sm); }
    .nav-links.active { left: 0; }
    .nav-link { color: var(--c-dark) !important; padding: 15px; width: 100%; text-align: center; }
    
    .mobile-toggle { display: block; color: white; }
    .navbar.scrolled .mobile-toggle { color: var(--c-primary); }
    .hero-title { font-size: 2.2rem; margin-bottom: 15px;}
    .hero-subtitle { font-size: 1.05rem; margin-bottom: 30px; }
    .hero-buttons { flex-direction: column; width: 100%; }
    .hero-buttons .btn { width: 100%; }
    .hero-bottom-stats { position: relative; bottom: 0; transform: none; width: 95%; margin: 20px auto 30px; grid-template-columns: 1fr; }
    .stat-box { border-right: none; border-bottom: 1px solid var(--c-gray); padding: 20px;}
    .contact-info-block { padding-right: 0;}
}

/* Floating Contact Widget */
.floating-contact {
    position: fixed;
    bottom: 30px;
    right: 30px;
    display: flex;
    flex-direction: column;
    gap: 15px;
    z-index: 9999;
}
.f-btn {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 1.8rem;
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
    text-decoration: none;
    position: relative;
}
.f-btn:hover {
    transform: scale(1.1);
    color: white;
}
.f-btn.zalo {
    background-color: #0068ff;
    font-family: Arial, sans-serif;
    font-weight: bold;
    font-size: 1.2rem;
}
.f-btn.facebook {
    background-color: #1877f2;
}
.f-btn.phone {
    background-color: #059669;
    animation: pulse-ring 2s infinite;
}
.f-btn .tooltip-text {
    position: absolute;
    right: 75px;
    background: rgba(0,0,0,0.8);
    color: white;
    padding: 6px 12px;
    border-radius: 4px;
    font-size: 0.9rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: 0.3s;
    font-weight: normal;
}
.f-btn:hover .tooltip-text {
    opacity: 1;
}
@keyframes pulse-ring {
    0% { box-shadow: 0 0 0 0 rgba(5, 150, 105, 0.7); }
    70% { box-shadow: 0 0 0 15px rgba(5, 150, 105, 0); }
    100% { box-shadow: 0 0 0 0 rgba(5, 150, 105, 0); }
}