/* Global Styles and Variables */
:root {
    /* Color Palette */
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --primary-light: #818cf8;
    --secondary: #06b6d4;
    --accent: #f59e0b;
    --success: #10b981;
    --danger: #ef4444;
    
    /* Neutral Colors */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Format Colors */
    --format-dd: #10b981;
    --format-mm: #3b82f6;
    --format-yy: #f59e0b;
    
    /* Typography */
    --font-display: 'Outfit', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Courier New', monospace;
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 1.5rem;
    --space-lg: 2rem;
    --space-xl: 3rem;
    --space-2xl: 4rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-display);
    font-size: 16px;
    line-height: 1.6;
    color: var(--gray-900);
    background: linear-gradient(180deg, #ffffff 0%, #f9fafb 100%);
    min-height: 100vh;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1rem;
}

h1 { font-size: clamp(2.5rem, 5vw, 4rem); }
h2 { font-size: clamp(2rem, 4vw, 3rem); }
h3 { font-size: clamp(1.5rem, 3vw, 2rem); }
h4 { font-size: clamp(1.25rem, 2.5vw, 1.5rem); }

p {
    margin-bottom: 1rem;
    color: var(--gray-600);
}

a {
    text-decoration: none;
    color: var(--primary);
    transition: color 0.2s ease;
}

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

/* Navigation */
.nav-container {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--gray-200);
}

.nav-content {
    max-width: 1280px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--gray-900);
}

.logo-icon {
    color: var(--primary);
    animation: pulse 2s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.logo-text {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    color: var(--gray-600);
    font-weight: 500;
    transition: color 0.2s ease;
}

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

.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--gray-600);
    transition: all 0.3s ease;
}

/* Hero Section */
.hero {
    position: relative;
    min-height: 80vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    inset: 0;
    z-index: -1;
}

.grid-pattern {
    position: absolute;
    inset: 0;
    background-image: 
        linear-gradient(var(--gray-200) 1px, transparent 1px),
        linear-gradient(90deg, var(--gray-200) 1px, transparent 1px);
    background-size: 50px 50px;
    opacity: 0.3;
}

.floating-dates {
    position: absolute;
    inset: 0;
}

.floating-date {
    position: absolute;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--gray-400);
    animation: float 20s ease-in-out infinite;
}

.floating-date:nth-child(1) { top: 10%; left: 10%; animation-delay: 0s; }
.floating-date:nth-child(2) { top: 20%; right: 15%; animation-delay: 3s; }
.floating-date:nth-child(3) { bottom: 30%; left: 20%; animation-delay: 6s; }
.floating-date:nth-child(4) { bottom: 20%; right: 25%; animation-delay: 9s; }
.floating-date:nth-child(5) { top: 50%; left: 5%; animation-delay: 12s; }
.floating-date:nth-child(6) { top: 60%; right: 10%; animation-delay: 15s; }

@keyframes float {
    0%, 100% { transform: translateY(0) rotate(0deg); opacity: 0.3; }
    50% { transform: translateY(-20px) rotate(5deg); opacity: 0.6; }
}

.hero-content {
    text-align: center;
    padding: 2rem;
    max-width: 900px;
    z-index: 1;
}

.hero-title {
    margin-bottom: 2rem;
    animation: fadeInUp 0.8s ease;
}

.title-line {
    display: block;
    line-height: 1.1;
}

.title-line.accent {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.25rem;
    color: var(--gray-600);
    margin-bottom: 2rem;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-cta {
    display: flex;
    gap: 1rem;
    justify-content: center;
    animation: fadeInUp 0.8s ease 0.4s both;
}

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 2rem;
    border-radius: var(--radius-lg);
    font-weight: 600;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
    box-shadow: 0 4px 14px 0 rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px 0 rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    background: white;
    color: var(--primary);
    border: 2px solid var(--gray-200);
}

.btn-secondary:hover {
    background: var(--gray-50);
    border-color: var(--primary);
}

/* Sections */
.section {
    padding: 4rem 0;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    margin-bottom: 1rem;
}

.section-header p {
    font-size: 1.125rem;
    color: var(--gray-600);
}

/* Converter Section */
.converter-section {
    background: linear-gradient(180deg, var(--gray-50) 0%, white 100%);
}

.converter-container {
    background: white;
    border-radius: var(--radius-2xl);
    padding: 2rem;
    box-shadow: var(--shadow-xl);
    border: 1px solid var(--gray-200);
}

.input-section {
    margin-bottom: 2rem;
}

.input-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--gray-700);
}

.date-input {
    width: 100%;
    padding: 1rem;
    font-size: 1.125rem;
    border: 2px solid var(--gray-200);
    border-radius: var(--radius-lg);
    font-family: var(--font-mono);
    transition: all 0.2s ease;
}

.date-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.input-helpers {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

.helper-btn {
    padding: 0.5rem 1rem;
    background: var(--gray-100);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

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

.calendar-picker {
    padding: 0.5rem 1rem;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    cursor: pointer;
}

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

.format-card {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    transition: all 0.3s ease;
}

.format-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary);
}

.format-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.format-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.copy-btn {
    padding: 0.25rem;
    background: none;
    border: none;
    cursor: pointer;
    color: var(--gray-400);
    transition: color 0.2s ease;
}

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

.copy-btn.copied {
    color: var(--success);
}

.format-value {
    font-family: var(--font-mono);
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
}

.format-pattern {
    font-size: 0.875rem;
    color: var(--gray-500);
    font-family: var(--font-mono);
}

/* Formats Section */
.formats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
}

.format-guide-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 2rem;
    border: 1px solid var(--gray-200);
    transition: all 0.3s ease;
}

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

.format-icon {
    width: 48px;
    height: 48px;
    margin-bottom: 1rem;
    color: var(--primary);
}

.format-description {
    color: var(--gray-600);
    margin-bottom: 1rem;
}

.format-examples {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.example-tag {
    padding: 0.25rem 0.75rem;
    background: var(--gray-100);
    border-radius: var(--radius-md);
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--gray-700);
}

.format-usage {
    font-size: 0.875rem;
    color: var(--gray-500);
    border-top: 1px solid var(--gray-200);
    padding-top: 1rem;
}

/* Regions Section */
.regions-section {
    background: linear-gradient(180deg, white 0%, var(--gray-50) 100%);
}

.world-map-container {
    background: white;
    border-radius: var(--radius-xl);
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-md);
}

.map-legend {
    display: flex;
    gap: 2rem;
    justify-content: center;
    margin-bottom: 2rem;
}

.legend-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.legend-color {
    width: 20px;
    height: 20px;
    border-radius: var(--radius-sm);
}

.world-map {
    width: 100%;
    height: auto;
    max-height: 400px;
}

.region-dd { fill: var(--format-dd); opacity: 0.7; }
.region-mm { fill: var(--format-mm); opacity: 0.7; }
.region-yy { fill: var(--format-yy); opacity: 0.7; }

.regions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
}

.region-card {
    background: white;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    border: 1px solid var(--gray-200);
}

.region-format {
    font-family: var(--font-mono);
    font-size: 1.125rem;
    color: var(--primary);
    margin: 0.5rem 0;
}

/* Programming Section */
.programming-section {
    background: var(--gray-900);
    color: white;
}

.programming-section .section-header h2,
.programming-section .section-header p {
    color: white;
}

.code-tabs {
    background: var(--gray-800);
    border-radius: var(--radius-xl);
    overflow: hidden;
}

.tab-buttons {
    display: flex;
    background: var(--gray-700);
    overflow-x: auto;
}

.tab-btn {
    padding: 1rem 1.5rem;
    background: none;
    border: none;
    color: var(--gray-400);
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.tab-btn:hover {
    color: white;
    background: var(--gray-600);
}

.tab-btn.active {
    color: white;
    background: var(--gray-800);
    border-bottom: 2px solid var(--primary);
}

.code-content {
    padding: 2rem;
}

.code-panel {
    display: none;
}

.code-panel.active {
    display: block;
}

.code-panel pre {
    background: var(--gray-900);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    overflow-x: auto;
}

.code-panel code {
    font-family: var(--font-mono);
    font-size: 0.875rem;
    line-height: 1.6;
    color: #e0e0e0;
}

/* Standards Section */
.standards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.standard-card {
    background: white;
    border-radius: var(--radius-xl);
    padding: 2rem;
    border: 1px solid var(--gray-200);
    transition: all 0.3s ease;
}

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

.standard-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.standard-badge {
    padding: 0.25rem 0.75rem;
    background: var(--primary);
    color: white;
    border-radius: var(--radius-md);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.standard-examples {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--gray-200);
}

.standard-examples code {
    display: block;
    padding: 0.25rem 0;
    font-family: var(--font-mono);
    font-size: 0.875rem;
    color: var(--gray-600);
}

/* Resources Section */
.resources-section {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
    color: white;
}

.resources-section .section-header h2,
.resources-section .section-header p {
    color: white;
}

.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.resource-link {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: 2rem;
    border-radius: var(--radius-lg);
    text-align: center;
    color: white;
    transition: all 0.3s ease;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

.resource-link:hover {
    background: rgba(255, 255, 255, 0.2);
    transform: translateY(-4px);
}

.resource-icon {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.resource-link h4 {
    color: white;
    margin-bottom: 0.5rem;
}

.resource-link p {
    color: rgba(255, 255, 255, 0.8);
    font-size: 0.875rem;
}

/* FAQ Section */
.faq-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 1rem;
}

.faq-item {
    background: white;
    border-radius: var(--radius-lg);
    border: 1px solid var(--gray-200);
    padding: 1.5rem;
    transition: all 0.3s ease;
}

.faq-item:hover {
    box-shadow: var(--shadow-md);
}

.faq-item summary {
    font-weight: 600;
    cursor: pointer;
    list-style: none;
    position: relative;
    padding-right: 2rem;
}

.faq-item summary::after {
    content: '+';
    position: absolute;
    right: 0;
    top: 0;
    font-size: 1.5rem;
    color: var(--primary);
    transition: transform 0.3s ease;
}

.faq-item[open] summary::after {
    transform: rotate(45deg);
}

.faq-item p {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--gray-200);
}

/* Footer */
.footer {
    background: var(--gray-900);
    color: white;
    padding: 3rem 0 1rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    margin-bottom: 1rem;
}

.footer-section p {
    color: var(--gray-400);
}

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

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

.footer-links a {
    color: var(--gray-400);
    transition: color 0.2s ease;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid var(--gray-800);
    color: var(--gray-500);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-cta {
        flex-direction: column;
        align-items: center;
    }
    
    .formats-grid,
    .standards-grid {
        grid-template-columns: 1fr;
    }
    
    .faq-grid {
        grid-template-columns: 1fr;
    }
    
    .tab-buttons {
        overflow-x: scroll;
    }
}

/* Animations */
@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

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

/* Utility Classes */
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }