/* ============================================
   GLOBAL STYLES - Dr. AI Premium Website
   High-End, Executive, Professional Design
   ============================================ */

/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Brand Colors */
    --primary-blue: #2E7BB4;
    --dark-blue: #1A4D7A;
    --accent-blue: #3A9DD9;
    --deep-blue: #0D2E4D;
    
    /* Neutral Colors */
    --white: #ffffff;
    --off-white: #fafafa;
    --light-gray: #f5f5f5;
    --medium-gray: #e0e0e0;
    --text-dark: #1a1a1a;
    --text-medium: #555555;
    --text-light: #888888;
    
    /* Semantic Colors */
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    
    /* Shadows */
    --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.16);
    --shadow-xl: 0 12px 48px rgba(0, 0, 0, 0.2);
    --shadow-hover: 0 16px 56px rgba(0, 0, 0, 0.24);
    
    /* Spacing */
    --space-xs: 8px;
    --space-sm: 16px;
    --space-md: 24px;
    --space-lg: 32px;
    --space-xl: 48px;
    --space-2xl: 64px;
    --space-3xl: 96px;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    color: var(--text-dark);
    background-color: var(--white);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: 'Poppins', sans-serif;
    font-weight: 700;
    line-height: 1.2;
    color: var(--text-dark);
    margin-bottom: var(--space-md);
}

h1 {
    font-size: clamp(2.5rem, 5vw, 3.5rem);
    letter-spacing: -1px;
}

h2 {
    font-size: clamp(2rem, 4vw, 2.75rem);
    letter-spacing: -0.5px;
}

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

h4 {
    font-size: clamp(1.25rem, 2.5vw, 1.5rem);
}

p {
    margin-bottom: var(--space-md);
    color: var(--text-medium);
    font-size: 1.0625rem;
    line-height: 1.7;
}

a {
    color: var(--primary-blue);
    text-decoration: none;
    transition: color var(--transition-base);
}

a:hover {
    color: var(--accent-blue);
}

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

.container-narrow {
    max-width: 800px;
}

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

/* Navigation */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: all var(--transition-smooth);
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

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

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: 'Poppins', sans-serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-blue);
    text-decoration: none;
}

.nav-logo {
    height: 40px;
    width: auto;
}

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

.nav-link {
    font-weight: 500;
    font-size: 1rem;
    color: var(--text-dark);
    padding: var(--space-xs) var(--space-sm);
    border-radius: var(--radius-sm);
    transition: all var(--transition-base);
    position: relative;
}

.nav-link:hover {
    color: var(--primary-blue);
    background: rgba(46, 123, 180, 0.05);
}

.nav-link.active {
    color: var(--primary-blue);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 50%;
    transform: translateX(-50%);
    width: 24px;
    height: 3px;
    background: var(--primary-blue);
    border-radius: var(--radius-full);
}

.nav-cta {
    background: linear-gradient(135deg, var(--primary-blue), var(--accent-blue));
    color: var(--white) !important;
    padding: 10px 24px !important;
    border-radius: var(--radius-full);
    font-weight: 600;
    box-shadow: var(--shadow-sm);
    transition: all var(--transition-smooth);
}

.nav-cta:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    background: linear-gradient(135deg, var(--accent-blue), var(--primary-blue)) !important;
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--space-xs);
}

.nav-toggle span {
    width: 28px;
    height: 3px;
    background: var(--text-dark);
    border-radius: var(--radius-full);
    transition: all var(--transition-base);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-xs);
    padding: 14px 32px;
    font-family: 'Poppins', sans-serif;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-md);
    border: none;
    cursor: pointer;
    text-decoration: none;
    transition: all var(--transition-smooth);
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-blue), var(--accent-blue));
    color: var(--white);
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: var(--white);
}

.btn-secondary {
    background: var(--white);
    color: var(--primary-blue);
    border: 2px solid var(--primary-blue);
}

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

.btn-large {
    padding: 18px 40px;
    font-size: 1.125rem;
}

.btn-icon {
    font-size: 1.2rem;
}

/* Cards */
.card {
    background: var(--white);
    border-radius: var(--radius-lg);
    padding: var(--space-xl);
    box-shadow: var(--shadow-md);
    transition: all var(--transition-smooth);
}

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

.card-header {
    margin-bottom: var(--space-lg);
}

.card-title {
    font-size: 1.5rem;
    margin-bottom: var(--space-sm);
}

.card-description {
    color: var(--text-medium);
    font-size: 1rem;
}

/* Sections */
.section {
    padding: var(--space-3xl) 0;
}

.section-alt {
    background: var(--off-white);
}

.section-gradient {
    background: linear-gradient(135deg, #2E7BB4 0%, #1A4D7A 50%, #0D2E4D 100%);
    color: var(--white);
}

.section-gradient h2,
.section-gradient h3,
.section-gradient p {
    color: var(--white);
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-2xl);
}

.section-title {
    margin-bottom: var(--space-md);
}

.section-subtitle {
    font-size: 1.25rem;
    color: var(--text-medium);
    max-width: 700px;
    margin: 0 auto;
}

/* Footer */
.footer {
    background: var(--dark-blue);
    color: rgba(255, 255, 255, 0.9);
    padding: var(--space-2xl) 0 var(--space-lg);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-xl);
    margin-bottom: var(--space-xl);
}

.footer-section h4 {
    color: var(--white);
    margin-bottom: var(--space-md);
    font-size: 1.125rem;
}

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

.footer-links li {
    margin-bottom: var(--space-sm);
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    transition: color var(--transition-base);
}

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

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: var(--space-lg);
    text-align: center;
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.7);
}

/* Utility Classes */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-0 { margin-top: 0; }
.mb-0 { margin-bottom: 0; }
.mt-sm { margin-top: var(--space-sm); }
.mb-sm { margin-bottom: var(--space-sm); }
.mt-md { margin-top: var(--space-md); }
.mb-md { margin-bottom: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mb-lg { margin-bottom: var(--space-lg); }
.mt-xl { margin-top: var(--space-xl); }
.mb-xl { margin-bottom: var(--space-xl); }

.grid {
    display: grid;
    gap: var(--space-lg);
}

.grid-2 { grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); }

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.animate-fade-in {
    animation: fadeIn 0.6s ease-out;
}

.animate-fade-in-up {
    animation: fadeInUp 0.8s ease-out;
}

.animate-fade-in-down {
    animation: fadeInDown 0.8s ease-out;
}

.animate-scale-in {
    animation: scaleIn 0.6s ease-out;
}

/* Responsive Design */
@media (max-width: 968px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        padding: var(--space-lg);
        box-shadow: var(--shadow-lg);
        gap: var(--space-sm);
    }
    
    .nav-menu.active {
        display: flex;
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .nav-link.active::after {
        display: none;
    }
    
    .section {
        padding: var(--space-2xl) 0;
    }
}

@media (max-width: 640px) {
    .container {
        padding: 0 var(--space-md);
    }
    
    .card {
        padding: var(--space-lg);
    }
    
    .section {
        padding: var(--space-xl) 0;
    }
    
    .btn {
        padding: 12px 24px;
        font-size: 0.9375rem;
    }
}