/* ========================================
   DIGITAL TWIN AI - PROFESSIONAL DESIGN SYSTEM
   ======================================== */

/* === ROOT VARIABLES === */
:root {
    /* Colors from digitaltwinai.co.uk */
    --navy-dark: #0A1F35;
    --navy-primary: #0F2942;
    --navy-medium: #1A3A52;
    --navy-light: #2A4A62;
    
    --lime-primary: #9EFA73;
    --lime-hover: #8EE963;
    --lime-light: #B8FBA3;
    
    --gray-50: #F9FAFB;
    --gray-100: #F3F4F6;
    --gray-200: #E5E7EB;
    --gray-300: #D1D5DB;
    --gray-600: #4B5563;
    --gray-700: #374151;
    --gray-800: #1F2937;
    
    --white: #FFFFFF;
    
    /* Typography */
    --font-primary: 'Montserrat', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* === RESET & BASE === */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-primary);
    font-size: 16px;
    line-height: 1.6;
    color: var(--gray-700);
    background: var(--white);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

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

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

/* === TYPOGRAPHY === */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--navy-dark);
    margin-bottom: var(--spacing-md);
}

h1 {
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 800;
    letter-spacing: -0.02em;
}

h2 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
}

h3 {
    font-size: clamp(1.5rem, 3vw, 2rem);
    font-weight: 600;
}

h4 {
    font-size: 1.25rem;
    font-weight: 600;
}

p {
    margin-bottom: var(--spacing-md);
    font-size: 1.125rem;
    line-height: 1.75;
    color: var(--gray-600);
}

.text-large {
    font-size: 1.25rem;
    line-height: 1.8;
}

.text-small {
    font-size: 0.875rem;
}

/* === LAYOUT === */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.container-wide {
    max-width: 1400px;
}

.section {
    padding: var(--spacing-3xl) 0;
}

.section-sm {
    padding: var(--spacing-2xl) 0;
}

.section-lg {
    padding: 5rem 0;
}

/* === NAVIGATION === */
.nav {
    background: var(--navy-primary);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
}

.nav-logo {
    height: 60px;
    width: auto;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
    align-items: center;
}

.nav-link {
    color: var(--white);
    font-weight: 500;
    font-size: 0.9375rem;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-base);
}

.nav-link:hover,
.nav-link.active {
    color: var(--lime-primary);
    background: rgba(158, 250, 115, 0.1);
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    display: block;
    width: 25px;
    height: 3px;
    background-color: var(--white);
    margin: 5px 0;
    transition: all 0.3s ease;
}

/* === HERO SECTION === */
.hero {
    background: linear-gradient(135deg, var(--navy-dark) 0%, var(--navy-primary) 50%, var(--navy-medium) 100%);
    color: var(--white);
    padding: var(--spacing-3xl) 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="60" height="60" xmlns="http://www.w3.org/2000/svg"><rect width="1" height="1" fill="%239EFA73" opacity="0.1"/></svg>');
    background-size: 60px 60px;
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    text-align: center;
}

.hero-title {
    color: var(--white);
    margin-bottom: var(--spacing-md);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.hero-subtitle {
    font-size: 1.25rem;
    line-height: 1.8;
    color: rgba(255, 255, 255, 0.9);
    max-width: 800px;
    margin: 0 auto var(--spacing-xl);
}

.hero-image {
    margin-top: var(--spacing-xl);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
}

.hero-image img {
    width: 100%;
    height: auto;
}

/* === BUTTONS === */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
    cursor: pointer;
    border: 2px solid transparent;
    text-align: center;
}

.btn-primary {
    background: var(--lime-primary);
    color: var(--navy-dark);
    border-color: var(--lime-primary);
}

.btn-primary:hover {
    background: var(--lime-hover);
    border-color: var(--lime-hover);
    transform: translateY(-2px);
    box-shadow: 0 8px 16px rgba(158, 250, 115, 0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--white);
    border-color: var(--white);
}

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

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

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

.btn-large {
    padding: 1.125rem 2.5rem;
    font-size: 1.125rem;
}

.btn-group {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

/* === CARDS === */
.card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-base);
    height: 100%;
    color: var(--gray-700);
}

.card h3, .card h4 {
    color: var(--navy-dark);
}

.card p {
    color: var(--gray-600);
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.card-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: 1.5rem;
    color: var(--navy-dark);
    margin-bottom: var(--spacing-sm);
}

.card-description {
    color: var(--gray-600);
    line-height: 1.6;
}

/* === GRIDS === */
.grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-xl);
}

.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.grid-4 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

/* === STATS === */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin: var(--spacing-xl) 0;
}

.stat-card {
    text-align: center;
    padding: var(--spacing-xl);
    background: var(--gray-50);
    border-radius: var(--radius-lg);
    border: 1px solid var(--gray-200);
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    color: var(--lime-primary);
    line-height: 1;
    margin-bottom: var(--spacing-sm);
}

.stat-label {
    font-size: 1rem;
    color: var(--gray-600);
    font-weight: 500;
}

/* === FEATURE SECTION === */
.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
}

.feature-card {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-lg);
    border: 1px solid var(--gray-200);
    transition: all var(--transition-base);
    color: var(--gray-700);
}

.feature-card h3 {
    color: var(--navy-dark);
}

.feature-card p {
    color: var(--gray-600);
}

.feature-card:hover {
    border-color: var(--lime-primary);
    box-shadow: 0 8px 24px rgba(158, 250, 115, 0.15);
    transform: translateY(-4px);
}

.feature-icon {
    width: 56px;
    height: 56px;
    background: linear-gradient(135deg, var(--lime-primary), var(--lime-hover));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
    font-size: 1.75rem;
}

.feature-title {
    font-size: 1.25rem;
    color: var(--navy-dark);
    margin-bottom: var(--spacing-sm);
}

.feature-description {
    color: var(--gray-600);
    line-height: 1.6;
}

/* === SECTION BACKGROUNDS === */
.section-dark {
    background: var(--navy-primary);
    color: var(--white);
}

.section-dark h2,
.section-dark h3,
.section-dark h4 {
    color: var(--white);
}

.section-dark p {
    color: rgba(255, 255, 255, 0.85);
}

/* Ensure cards in dark sections have proper contrast */
.section-dark .card {
    background: var(--white);
    color: var(--gray-700);
}

.section-dark .card-title,
.section-dark .card h3,
.section-dark .card h4 {
    color: var(--navy-dark) !important;
}

.section-dark .card-description,
.section-dark .card p {
    color: var(--gray-600) !important;
}

.section-dark .btn-outline {
    background: transparent;
    color: var(--navy-primary);
}

.section-dark .btn-outline:hover {
    background: var(--navy-primary);
    color: var(--white);
}

.section-light {
    background: var(--gray-50);
}

.section-accent {
    background: linear-gradient(135deg, var(--lime-primary) 0%, var(--lime-hover) 100%);
    color: var(--navy-dark);
}

/* === IMAGE WITH OVERLAY === */
.image-overlay-container {
    position: relative;
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.image-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(to bottom, transparent 0%, rgba(10, 31, 53, 0.7) 100%);
}

/* === FOOTER === */
.footer {
    background: var(--navy-dark);
    color: var(--white);
    padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
}

.footer-section h4 {
    color: var(--lime-primary);
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

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

.footer-link {
    display: block;
    padding: var(--spacing-xs) 0;
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-base);
}

.footer-link:hover {
    color: var(--lime-primary);
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: var(--spacing-lg);
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.875rem;
}

/* === UTILITIES === */
.text-center {
    text-align: center;
}

.mb-4 {
    margin-bottom: var(--spacing-xl);
}

.mt-4 {
    margin-top: var(--spacing-xl);
}

.text-lime {
    color: var(--lime-primary);
}

/* === RESPONSIVE === */
@media (max-width: 992px) {
    .nav-toggle {
        display: block;
        z-index: 1001;
    }

    .nav-menu {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 300px;
        height: 100vh;
        background: var(--navy-dark);
        flex-direction: column;
        padding: 6rem 2rem 2rem 2rem;
        transition: right 0.3s ease-in-out;
        box-shadow: -5px 0 15px rgba(0,0,0,0.2);
        align-items: flex-start;
        z-index: 1000;
        overflow-y: auto; /* Enable vertical scrolling */
        -webkit-overflow-scrolling: touch; /* Smooth scrolling on iOS */
    }

    .nav-menu.active {
        right: 0;
    }

    .nav-link {
        font-size: 1.1rem;
        display: block;
        width: 100%;
        padding: 0.75rem 0;
        border-bottom: 1px solid rgba(255,255,255,0.1);
    }

    .nav-link:hover,
    .nav-link.active {
        background: transparent;
        color: var(--lime-primary);
        padding-left: 10px;
    }
}

@media (max-width: 768px) {
    .hero {
        padding: var(--spacing-2xl) 0;
    }
    
    .section {
        padding: var(--spacing-2xl) 0;
    }
    
    .btn-group {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
    
    .grid-2,
    .grid-3,
    .grid-4 {
        grid-template-columns: 1fr;
    }
}

/* Fix for feature cards inside dark sections */
.section-dark .feature-card {
    background: var(--white);
    color: var(--gray-700);
}

.section-dark .feature-card h3,
.section-dark .feature-card .feature-title {
    color: var(--navy-dark) !important;
}

.section-dark .feature-card p,
.section-dark .feature-card .feature-description {
    color: var(--gray-600) !important;
}

/* CRITICAL FIX: Force dark text on feature cards in dark sections */
.section-dark .feature-card h3,
.section-dark .feature-card .feature-title {
    color: var(--navy-dark) !important;
}

.section-dark .feature-card p,
.section-dark .feature-card .feature-description {
    color: var(--gray-600) !important;
}