/* ----------------------------------------------------
   DESIGN SYSTEM & VARIABLES (Flat Light Green Theme)
   ---------------------------------------------------- */
@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700;800&display=swap');

:root {
    --font-primary: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    
    /* Clean Light Flat Palette */
    --bg-main: #F8FAFC;
    --bg-card: #FFFFFF;
    --bg-card-hover: #FFFFFF;
    --border-color: #E2E8F0;
    --border-hover: #10B981; /* Green */
    
    /* Green Accents */
    --primary: #10B981; /* Emerald/Green */
    --primary-hover: #0D9668;
    --primary-light: #E6F4EA;
    
    --accent: #059669;
    --accent-light: #D1FAE5;

    --text-main: #0F172A;
    --text-muted: #64748B;
    --text-inverse: #FFFFFF;
    
    --success: #10B981;
    --warning: #F59E0B;
    
    --transition-fast: all 0.25s ease;
    --border-radius-sm: 6px;
    --border-radius-md: 12px;
    --border-radius-lg: 18px;
    --border-radius-xl: 24px;
}

/* Reset & Global */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    font-family: var(--font-primary);
    line-height: 1.6;
    overflow-x: hidden;
    position: relative;
}

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

/* Header & Navigation */
header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 100;
    background: #FFFFFF;
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
    letter-spacing: -0.03em;
}

.logo span {
    font-weight: 400;
    color: var(--text-main);
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: 2.5rem;
    list-style: none;
}

.nav-item a {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-muted);
}

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

.nav-cta {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.nav-cta-mobile {
    display: none;
}

/* Flat Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.65rem 1.25rem;
    border-radius: var(--border-radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition-fast);
    border: none;
    gap: 0.5rem;
}

.btn-primary {
    background-color: var(--primary);
    color: var(--text-inverse);
}

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

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

.btn-secondary:hover {
    background-color: rgba(15, 23, 42, 0.04);
    border-color: var(--text-muted);
}

/* Mobile Menu Toggle */
.mobile-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-main);
    font-size: 1.5rem;
    cursor: pointer;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Hero Section */
.hero {
    padding: 9rem 0 5rem;
    text-align: center;
    background-color: #FFFFFF;
    border-bottom: 1px solid var(--border-color);
}

.badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.4rem 0.9rem;
    background-color: var(--primary-light);
    border: 1px solid rgba(16, 185, 129, 0.2);
    border-radius: 4px;
    color: var(--primary-hover);
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.02em;
    margin-bottom: 1.5rem;
    color: var(--text-main);
}

.hero p {
    font-size: 1.15rem;
    color: var(--text-muted);
    max-width: 700px;
    margin: 0 auto 2.5rem;
    font-weight: 400;
}

.hero-ctas {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

/* Features Section */
.section-title {
    text-align: center;
    margin-bottom: 3.5rem;
}

.section-title h2 {
    font-size: 2.25rem;
    font-weight: 800;
    margin-bottom: 0.75rem;
    color: var(--text-main);
}

.section-title p {
    color: var(--text-muted);
    font-size: 1.05rem;
    max-width: 600px;
    margin: 0 auto;
}

.features {
    padding: 5rem 0;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

/* Flat Card Style */
.card {
    background-color: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 2rem;
    transition: var(--transition-fast);
}

.card:hover {
    border-color: var(--border-hover);
    box-shadow: 0 4px 12px rgba(15, 23, 42, 0.05);
}

.card-icon {
    width: 3rem;
    height: 3rem;
    background-color: var(--primary-light);
    border-radius: var(--border-radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.35rem;
    color: var(--primary);
    margin-bottom: 1.25rem;
}

.card h3 {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: 0.75rem;
    color: var(--text-main);
}

.card p {
    color: var(--text-muted);
    font-size: 0.9rem;
    line-height: 1.5;
}

/* Pricing Section */
.pricing {
    padding: 5rem 0;
    background-color: #FFFFFF;
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.5rem;
    align-items: stretch;
}

.price-card {
    position: relative;
    display: flex;
    flex-direction: column;
}

.price-card.popular {
    border: 2px solid var(--primary);
    background-color: #FFFFFF;
    box-shadow: 0 8px 24px rgba(16, 185, 129, 0.08);
}

.price-card.popular::after {
    content: 'PHỔ BIẾN NHẤT';
    position: absolute;
    top: -0.75rem;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--primary);
    font-size: 0.65rem;
    font-weight: 800;
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    letter-spacing: 0.05em;
    color: white;
}

.price-header {
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.25rem;
    margin-bottom: 1.5rem;
}

.price-name {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-muted);
    margin-bottom: 0.5rem;
}

.price-card.popular .price-name {
    color: var(--primary);
}

.price-amount {
    font-size: 2rem;
    font-weight: 800;
    color: var(--text-main);
}

.price-amount span {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-muted);
}

.price-features {
    list-style: none;
    margin-bottom: 2rem;
    flex-grow: 1;
}

.price-features li {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    font-size: 0.85rem;
    color: var(--text-muted);
}

.price-features li.included {
    color: var(--text-main);
}

.price-features li svg {
    color: var(--primary);
    flex-shrink: 0;
}

.price-cta {
    width: 100%;
}

/* OAuth Brand Verification Section */
.oauth-verify {
    padding: 5rem 0;
    background-color: var(--bg-main);
}

.oauth-container {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 3rem;
    align-items: center;
}

.oauth-content h2 {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: 1.25rem;
    color: var(--text-main);
}

.oauth-content p {
    color: var(--text-muted);
    margin-bottom: 1.25rem;
    line-height: 1.6;
}

.oauth-list {
    list-style: none;
    margin-top: 1.25rem;
}

.oauth-list li {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    font-size: 0.9rem;
}

.oauth-list li svg {
    color: var(--primary);
    margin-top: 0.2rem;
    flex-shrink: 0;
}

.oauth-visual {
    background-color: #FFFFFF;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-lg);
    padding: 2.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 1rem;
}

.oauth-badge {
    background-color: var(--bg-main);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 1rem;
    width: 100%;
    max-width: 320px;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.oauth-badge img {
    width: 2.25rem;
    height: 2.25rem;
}

.oauth-badge-info h4 {
    font-size: 0.9rem;
    font-weight: 700;
    color: var(--text-main);
}

.oauth-badge-info p {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* Legal Pages (Policy / Term) Styling */
.legal-page {
    padding: 8rem 0 5rem;
}

.legal-container {
    max-width: 800px;
    margin: 0 auto;
    background-color: #FFFFFF;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 3rem;
}

.legal-header {
    text-align: center;
    margin-bottom: 2.5rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.5rem;
}

.legal-header h1 {
    font-size: 2.25rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.legal-date {
    font-size: 0.85rem;
    color: var(--text-muted);
    font-style: italic;
}

.legal-content h2 {
    font-size: 1.35rem;
    font-weight: 700;
    margin: 2rem 0 0.75rem;
    color: var(--text-main);
    border-left: 4px solid var(--primary);
    padding-left: 0.5rem;
}

.legal-content p {
    color: var(--text-muted);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1.25rem;
}

.legal-content ul, .legal-content ol {
    margin-left: 1.25rem;
    margin-bottom: 1.25rem;
    color: var(--text-muted);
}

.legal-content li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
    font-size: 0.95rem;
}

.legal-content strong {
    color: var(--text-main);
}

/* Footer Section */
footer {
    border-top: 1px solid var(--border-color);
    background-color: #FFFFFF;
    padding: 4rem 0 2rem;
    margin-top: 2rem;
}

.footer-grid {
    display: grid;
    grid-template-columns: 1.5fr repeat(3, 1fr);
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-brand .logo {
    margin-bottom: 1rem;
}

.footer-brand p {
    color: var(--text-muted);
    font-size: 0.85rem;
    line-height: 1.5;
    margin-bottom: 1.25rem;
    max-width: 320px;
}

.footer-links h4 {
    font-size: 0.9rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1.25rem;
    color: var(--text-main);
}

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

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

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

.footer-links ul li a:hover {
    color: var(--primary);
}

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
}

.footer-bottom p {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.footer-legal-links {
    display: flex;
    gap: 1.5rem;
    font-size: 0.8rem;
    color: var(--text-muted);
}

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

/* Responsive Design */
@media (max-width: 968px) {
    .hero h1 {
        font-size: 2.75rem;
    }
    
    .oauth-container {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 2rem;
    }
}

@media (max-width: 768px) {
    .mobile-toggle {
        display: block;
    }
    
    .nav-menu {
        position: fixed;
        top: 4.2rem;
        left: -100%;
        width: 100%;
        height: calc(100vh - 4.2rem);
        background: #FFFFFF;
        flex-direction: column;
        align-items: flex-start;
        padding: 2.5rem 2rem;
        gap: 1.5rem;
        transition: 0.3s ease-in-out;
        border-top: 1px solid var(--border-color);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-cta {
        display: none;
    }
    
    .nav-menu .nav-cta-mobile {
        display: flex;
        flex-direction: column;
        width: 100%;
        gap: 0.75rem;
        margin-top: 1.5rem;
    }
    
    .hero h1 {
        font-size: 2.25rem;
    }
    
    .hero-ctas {
        flex-direction: column;
        align-items: stretch;
        max-width: 320px;
        margin: 0 auto 2rem;
    }
    
    .legal-container {
        padding: 1.5rem;
    }
    
    .legal-header h1 {
        font-size: 1.75rem;
    }
    
    .footer-grid {
        grid-template-columns: 1fr;
    }
}