/* ==========================================
   UAV Low-Altitude Economy Calculator
   Municipal Government Web Design
   ========================================== */

/* ==========================================
   CSS Variables - Government Color Palette
   ========================================== */
:root {
    /* Primary Colors - Professional Government Blue */
    --color-primary: #1e40af;
    --color-primary-dark: #1e3a8a;
    --color-primary-light: #3b82f6;
    
    /* Neutral Colors - Clean and Authoritative */
    --color-neutral-900: #111827;
    --color-neutral-800: #1f2937;
    --color-neutral-700: #374151;
    --color-neutral-600: #4b5563;
    --color-neutral-500: #6b7280;
    --color-neutral-400: #9ca3af;
    --color-neutral-300: #d1d5db;
    --color-neutral-200: #e5e7eb;
    --color-neutral-100: #f3f4f6;
    --color-neutral-50: #f9fafb;
    
    /* Accent Colors */
    --color-accent: #059669;
    --color-accent-light: #10b981;
    
    /* Semantic Colors */
    --color-success: #059669;
    --color-warning: #d97706;
    --color-error: #dc2626;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-base: 16px;
    --line-height-base: 1.6;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;
    
    /* Layout */
    --container-width: 1200px;
    --border-radius: 0.5rem;
    --box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --box-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-base: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* ==========================================
   Global Styles & Reset
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    line-height: var(--line-height-base);
    color: var(--color-neutral-800);
    background-color: #ffffff;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ==========================================
   Typography
   ========================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--color-neutral-900);
    margin-bottom: var(--spacing-sm);
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
}

h2 {
    font-size: 2rem;
    font-weight: 600;
}

h3 {
    font-size: 1.5rem;
}

h4 {
    font-size: 1.25rem;
}

p {
    margin-bottom: var(--spacing-sm);
    color: var(--color-neutral-700);
}

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

a:hover {
    color: var(--color-primary-dark);
}

a:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

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

/* Skip to content link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-sm);
    z-index: 100;
}

.skip-link:focus {
    top: 0;
}

/* ==========================================
   Header
   ========================================== */
.site-header {
    background: white;
    border-bottom: 1px solid var(--color-neutral-200);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: box-shadow var(--transition-base);
}

.site-header.scrolled {
    box-shadow: var(--box-shadow-lg);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) 0;
}

.logo h1 {
    font-size: 1.25rem;
    margin: 0;
    color: var(--color-primary);
}

.logo-subtitle {
    font-size: 0.875rem;
    color: var(--color-neutral-600);
    font-weight: 400;
}

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

.main-nav a {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-neutral-700);
    transition: color var(--transition-fast);
}

.main-nav a:hover {
    color: var(--color-primary);
}

.main-nav .nav-cta {
    padding: var(--spacing-xs) var(--spacing-md);
    background: var(--color-primary);
    color: white;
    border-radius: var(--border-radius);
    transition: background-color var(--transition-fast);
}

.main-nav .nav-cta:hover {
    background: var(--color-primary-dark);
    color: white;
}

/* ==========================================
   Hero Section
   ========================================== */
.hero {
    background: linear-gradient(135deg, var(--color-neutral-50) 0%, white 100%);
    padding: var(--spacing-3xl) 0 var(--spacing-2xl);
    border-bottom: 1px solid var(--color-neutral-200);
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

.hero-title {
    font-size: 2.75rem;
    font-weight: 700;
    color: var(--color-neutral-900);
    margin-bottom: var(--spacing-md);
    line-height: 1.1;
}

.hero-subtitle {
    font-size: 1.375rem;
    color: var(--color-neutral-700);
    font-weight: 400;
    margin-bottom: var(--spacing-xl);
    line-height: 1.5;
}

.context-statement {
    background: white;
    padding: var(--spacing-lg);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--color-primary);
    box-shadow: var(--box-shadow);
    margin-bottom: var(--spacing-xl);
    text-align: left;
}

.context-statement p {
    font-size: 1rem;
    color: var(--color-neutral-700);
    margin: 0;
    line-height: 1.7;
}

.hero-cta {
    margin-top: var(--spacing-xl);
}

/* ==========================================
   Buttons
   ========================================== */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: all var(--transition-base);
    font-family: var(--font-family);
}

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

.btn-primary:hover {
    background: var(--color-primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--box-shadow-lg);
}

.btn-primary:active {
    transform: translateY(0);
}

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

/* ==========================================
   Features Section
   ========================================== */
.features-section {
    padding: var(--spacing-3xl) 0;
    background: white;
}

.section-title {
    text-align: center;
    font-size: 2.25rem;
    margin-bottom: var(--spacing-xl);
    color: var(--color-neutral-900);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.feature-card {
    background: var(--color-neutral-50);
    padding: var(--spacing-xl);
    border-radius: var(--border-radius);
    border: 1px solid var(--color-neutral-200);
    transition: all var(--transition-base);
    opacity: 0;
    transform: translateY(20px);
}

.feature-card.fade-in {
    opacity: 1;
    transform: translateY(0);
}

.feature-card:hover {
    border-color: var(--color-primary-light);
    box-shadow: var(--box-shadow-lg);
    transform: translateY(-4px);
}

.feature-icon {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-primary);
    color: white;
    border-radius: var(--border-radius);
    margin-bottom: var(--spacing-md);
}

.feature-title {
    font-size: 1.375rem;
    margin-bottom: var(--spacing-sm);
    color: var(--color-neutral-900);
}

.feature-description {
    font-size: 1rem;
    color: var(--color-neutral-700);
    line-height: 1.7;
    margin: 0;
}

/* ==========================================
   Platform Section
   ========================================== */
.platform-section {
    background: var(--color-primary);
    color: white;
    padding: var(--spacing-2xl) 0;
}

.platform-section .section-title {
    color: white;
}

.platform-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.platform-description p {
    font-size: 1.25rem;
    line-height: 1.7;
    color: rgba(255, 255, 255, 0.95);
    margin: 0;
}

.platform-description strong {
    color: white;
    font-weight: 600;
}

/* ==========================================
   Resources Section
   ========================================== */
.resources-section {
    padding: var(--spacing-3xl) 0;
    background: var(--color-neutral-50);
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
}

.resource-card {
    background: white;
    padding: var(--spacing-xl);
    border-radius: var(--border-radius);
    border: 1px solid var(--color-neutral-200);
    transition: all var(--transition-base);
    display: block;
}

.resource-card:hover {
    border-color: var(--color-primary);
    box-shadow: var(--box-shadow-lg);
    transform: translateY(-4px);
}

.resource-card h3 {
    font-size: 1.25rem;
    color: var(--color-neutral-900);
    margin-bottom: var(--spacing-sm);
}

.resource-card p {
    font-size: 1rem;
    color: var(--color-neutral-600);
    margin-bottom: var(--spacing-md);
}

.resource-link {
    color: var(--color-primary);
    font-weight: 600;
    font-size: 0.9375rem;
}

.resource-card:hover .resource-link {
    color: var(--color-primary-dark);
}

/* ==========================================
   CTA Section
   ========================================== */
.cta-section {
    background: linear-gradient(135deg, var(--color-primary-dark) 0%, var(--color-primary) 100%);
    color: white;
    padding: var(--spacing-3xl) 0;
    text-align: center;
}

.cta-content h2 {
    color: white;
    font-size: 2.25rem;
    margin-bottom: var(--spacing-sm);
}

.cta-content p {
    font-size: 1.25rem;
    color: rgba(255, 255, 255, 0.9);
    margin-bottom: var(--spacing-xl);
}

.cta-section .btn-primary {
    background: white;
    color: var(--color-primary);
}

.cta-section .btn-primary:hover {
    background: var(--color-neutral-100);
    color: var(--color-primary-dark);
}

/* ==========================================
   Footer
   ========================================== */
.site-footer {
    background: var(--color-neutral-900);
    color: var(--color-neutral-400);
    padding: var(--spacing-2xl) 0 var(--spacing-lg);
}

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

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

.footer-section p {
    color: var(--color-neutral-400);
    font-size: 0.9375rem;
}

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

.footer-section ul li {
    margin-bottom: var(--spacing-xs);
}

.footer-section a {
    color: var(--color-neutral-400);
    font-size: 0.9375rem;
    transition: color var(--transition-fast);
}

.footer-section a:hover {
    color: white;
}

.footer-bottom {
    border-top: 1px solid var(--color-neutral-800);
    padding-top: var(--spacing-lg);
    text-align: center;
}

.footer-bottom p {
    color: var(--color-neutral-500);
    font-size: 0.875rem;
    margin: 0;
}

/* ==========================================
   Responsive Design
   ========================================== */

/* Tablet */
@media (max-width: 992px) {
    .hero-title {
        font-size: 2.25rem;
    }
    
    .hero-subtitle {
        font-size: 1.25rem;
    }
    
    .features-grid {
        grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    }
    
    .section-title {
        font-size: 2rem;
    }
}

/* Mobile */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .main-nav ul {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }
    
    .hero {
        padding: var(--spacing-2xl) 0;
    }
    
    .hero-title {
        font-size: 1.875rem;
    }
    
    .hero-subtitle {
        font-size: 1.125rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .resources-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
    
    h2 {
        font-size: 1.75rem;
    }
    
    .section-title {
        font-size: 1.75rem;
    }
}

@media (max-width: 480px) {
    :root {
        --font-size-base: 15px;
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
    
    .hero-title {
        font-size: 1.625rem;
    }
    
    .feature-card,
    .resource-card {
        padding: var(--spacing-lg);
    }
}

/* ==========================================
   Accessibility
   ========================================== */

/* Focus styles */
button:focus,
a:focus {
    outline: 2px solid var(--color-primary);
    outline-offset: 2px;
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
        scroll-behavior: auto !important;
    }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --color-neutral-700: #000000;
        --color-neutral-600: #1a1a1a;
    }
    
    .feature-card,
    .resource-card {
        border-width: 2px;
    }
}

/* ==========================================
   Print Styles
   ========================================== */
@media print {
    .site-header,
    .site-footer,
    .hero-cta,
    .cta-section {
        display: none;
    }
    
    body {
        font-size: 12pt;
    }
    
    .container {
        max-width: 100%;
    }
}