* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

/* BIẾN MÀU SẮC CHÍNH */
:root {
    --primary: #2563eb;
    --secondary: #f59e0b;
    --accent: #10b981;
    --dark: #1e293b;
    --light: #f8fafc;
    --gray: #64748b;
}

body {
    background: var(--light);
    color: var(--dark);
    line-height: 1.4;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* NÚT ĐĂNG NHẬP - Glass morphism effect */
.login-button {
    position: absolute;
    top: 5px;
    right: 5px;
    background: rgba(255,255,255,0.25);
    padding: 4px 10px;
    border-radius: 6px;
    backdrop-filter: blur(6px);
    font-size: 12px;
    text-decoration: none;
    color: white;
    font-weight: 600;
    transition: 0.3s;
    border: 1px solid rgba(255,255,255,0.35);
    cursor: pointer;
}

.login-button:hover {
    background: rgba(255,255,255,0.4);
}

.login-button.loading {
    background: rgba(255,255,255,0.6);
    pointer-events: none;
}

.loading-spinner {
    display: inline-block;
    width: 12px;
    height: 12px;
    border: 2px solid transparent;
    border-top: 2px solid var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-right: 5px;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* HEADER/HERO - Gradient xanh lam */
.modern-hero {
    background: linear-gradient(135deg, var(--primary) 0%, #1e40af 100%);
    color: white;
    padding: 15px 0 10px;
    text-align: center;
    position: relative;
    overflow: hidden;
    min-height: 80px;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

/* Hiệu ứng particle nền */
.modern-hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: float 8s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translate(0, 0) rotate(0deg); }
    33% { transform: translate(30px, -20px) rotate(120deg); }
    66% { transform: translate(-20px, 20px) rotate(240deg); }
}

.modern-hero h1 {
    font-size: 1.5rem;
    margin-bottom: 0.3rem;
    font-weight: 700;
}

.hero-subtitle {
    font-size: 0.75rem;
    margin-bottom: 0;
    opacity: 0.9;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

/* THỐNG KÊ NHANH */
.quick-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    margin-top: 1.5rem;
    padding: 0 15px;
}

.stat-item {
    text-align: center;
}

.stat-icon {
    font-size: 1.3rem;
    margin-bottom: 0.3rem;
    opacity: 0.9;
}

.stat-number {
    font-size: 1.1rem;
    font-weight: bold;
    margin-bottom: 0.2rem;
}

.stat-label {
    font-size: 0.7rem;
    opacity: 0.8;
}

/* PHẦN SO SÁNH CÔNG NGHỆ */
.tech-comparison {
    padding: 40px 0;
    background: white;
}

.comparison-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-top: 1.5rem;
}

.tech-card {
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 6px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s;
    border-top: 3px solid transparent;
}

.tech-card:hover {
    transform: translateY(-2px);
}

.offset-card {
    border-top-color: var(--primary);
}

.digital-card {
    border-top-color: var(--secondary);
}

.card-header {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 1rem;
}

.tech-icon {
    width: 40px;
    height: 40px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    color: white;
}

.offset-icon {
    background: linear-gradient(135deg, var(--primary), #1e40af);
}

.digital-icon {
    background: linear-gradient(135deg, var(--secondary), #d97706);
}

/* DANH SÁCH TÍNH NĂNG */
ul.feature-list {
    list-style: none;
    margin-bottom: 1rem;
    padding-left: 0;
}

.feature-list li {
    padding: 0.4rem 0;
    border-bottom: 1px solid #f1f5f9;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.8rem;
}

.feature-list li:before {
    content: "✓";
    color: var(--accent);
    font-weight: bold;
    font-size: 0.9rem;
}

/* RESPONSIVE */
@media (max-width: 768px) {
    .quick-stats {
        grid-template-columns: repeat(2, 1fr);
        gap: 0.8rem;
        margin-top: 1rem;
    }

    .comparison-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .modern-hero h1 {
        font-size: 1.2rem;
    }
    
    .modern-hero {
        padding: 12px 0 8px;
        min-height: 60px;
    }

    .hero-subtitle {
        font-size: 0.65rem;
    }

    .stat-icon {
        font-size: 1.1rem;
    }

    .stat-number {
        font-size: 0.9rem;
    }

    .stat-label {
        font-size: 0.6rem;
    }

    .tech-comparison {
        padding: 30px 0;
    }
}

/* =========================================== */
/* NAVIGATION STYLES - Di chuyển từ index.html */
/* =========================================== */

/* Simple responsive navbar + pricing styles */
.site-nav {
    background: rgba(255,255,255,0.95);
    box-shadow: 0 2px 6px rgba(0,0,0,0.06);
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 40;
}

body {
    padding-top: 60px;
}

.site-nav .nav-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 16px;
}

.nav-links {
    display: flex;
    gap: 14px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-links li {
    list-style: none;
}

.nav-links a {
    color: #1d4ed8;
    text-decoration: none;
    padding: 6px 8px;
    border-radius: 6px;
    font-weight: 700;
}

/* Dropdown (desktop) */
.nav-links li {
    position: relative;
}

.submenu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: #fff;
    border: 1px solid rgba(0,0,0,0.06);
    box-shadow: 0 8px 24px rgba(0,0,0,0.12);
    padding: 8px 0;
    border-radius: 8px;
    z-index: 60;
}

.submenu li {
    padding: 0;
}

.submenu a {
    display: block;
    padding: 8px 12px;
    color: #1d4ed8;
    white-space: nowrap;
}

.submenu a:hover {
    background: rgba(29,78,216,0.08);
}

.caret {
    font-size: 12px;
    margin-left: 6px;
    color: #1d4ed8;
    display: inline-block;
    transition: transform .2s ease;
}

.has-submenu.open .caret {
    transform: rotate(180deg);
}

/* Show submenu whenever parent li has .open (all breakpoints) */
.nav-links li.open > .submenu {
    display: block;
}

/* Nested submenu positioning (desktop) */
.submenu .submenu {
    top: 0;
    left: 100%;
}

/* Mobile submenu toggles - hidden, only use caret */
.submenu-toggle {
    display: none !important;
    background: none;
    border: 0;
    color: #1d4ed8;
    font-size: 16px;
    margin-left: 4px;
    min-width: 20px;
}

/* Login button in navigation */
.login-button {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: linear-gradient(135deg, #1d4ed8, #3b82f6);
    color: white !important;
    text-decoration: none;
    padding: 8px 20px;
    border-radius: 20px;
    font-weight: 700;
    font-size: 14px;
    transition: all 0.3s ease;
    box-shadow: 0 2px 8px rgba(29,78,216,0.3);
    position: static; /* Override previous absolute positioning */
    top: auto;
    right: auto;
    background: linear-gradient(135deg, #1d4ed8, #3b82f6); /* Override glass effect */
    backdrop-filter: none;
    border: none;
}

.login-button:hover {
    background: linear-gradient(135deg, #1e40af, #2563eb);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(29,78,216,0.4);
}

.login-icon {
    font-size: 16px;
}

.nav-toggle {
    display: none;
    background: none;
    border: 0;
    font-size: 20px;
}

/* Responsive navigation */
@media (max-width: 900px) {
    /* off-canvas left menu */
    .nav-links {
        display: flex;
        flex-direction: column;
        position: fixed;
        top: 56px;
        left: 0;
        bottom: 0;
        width: 260px;
        transform: translateX(-100%);
        transition: transform .28s ease;
        background: #ffffff;
        padding: 16px;
        gap: 8px;
        box-shadow: 0 6px 24px rgba(0,0,0,0.12);
        z-index: 50;
    }
    
    .nav-links li {
        padding: 8px 0;
    }
    
    .nav-links.open {
        transform: translateX(0);
    }
    
    .nav-toggle {
        display: inline-flex;
    }

    /* Mobile accordion: collapsed by default, clear hierarchy */
    .submenu {
        position: static;
        display: none;
        border: 0;
        box-shadow: none;
        padding: 6px 0;
        margin-left: 8px;
        border-left: 2px solid rgba(29,78,216,0.15);
        background: rgba(29,78,216,0.03);
    }
    
    .submenu .submenu {
        margin-left: 12px;
        border-left: 1px solid rgba(29,78,216,0.12);
    }
    
    /* Parent emphasis */
    .has-submenu > a {
        font-weight: 700;
        color: #1d4ed8;
        border-radius: 6px;
        padding: 8px 10px;
        display: flex;
        align-items: center;
        justify-content: space-between;
    }
    

    
    /* Child link lighter weight */
    .submenu a {
        font-weight: 600;
        color: #1d4ed8;
        padding: 8px 10px;
    }
    
    .submenu .submenu a {
        font-weight: 500;
        color: #1d4ed8;
        padding-left: 12px;
    }
    
    .nav-links li.open > .submenu {
        display: block;
    }
    
    .submenu-toggle {
        display: inline-flex !important;
        align-items: center;
        justify-content: center;
        min-width: 24px;
        padding: 4px;
        font-size: 16px;
        color: #1d4ed8;
        font-weight: 700;
        background: none;
        border: 1px solid rgba(29,78,216,0.2);
        border-radius: 6px;
        margin-left: 6px;
    }
}