/* ===================================
   AI Carbon Footprint Calculator
   Modern, Eco-Friendly Design
   =================================== */

/* CSS Variables for Theme */
:root {
    /* Eco-friendly Color Palette */
    --primary-green: #2d6a4f;
    --secondary-green: #40916c;
    --light-green: #52b788;
    --pale-green: #95d5b2;
    --mint: #d8f3dc;
    
    --primary-blue: #0077b6;
    --secondary-blue: #00b4d8;
    --light-blue: #90e0ef;
    
    --dark-bg: #1b4332;
    --darker-bg: #081c15;
    --light-bg: #f8f9fa;
    --white: #ffffff;
    
    --text-dark: #212529;
    --text-light: #6c757d;
    --text-white: #ffffff;
    
    --warning: #f77f00;
    --danger: #d62828;
    --success: #52b788;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-xxl: 4rem;
    
    /* Typography */
    --font-primary: 'Inter', sans-serif;
    --font-heading: 'Poppins', sans-serif;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-medium: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 40px rgba(0, 0, 0, 0.2);
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-family: var(--font-heading);
    font-weight: 700;
    line-height: 1.2;
    color: var(--dark-bg);
}

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, 1.75rem); }

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

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

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

/* Header & Navigation */
.header {
    background: linear-gradient(135deg, var(--dark-bg) 0%, var(--primary-green) 100%);
    padding: var(--spacing-sm) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: var(--shadow-md);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--white);
    font-family: var(--font-heading);
}

.logo i {
    color: var(--mint);
    font-size: 1.75rem;
}

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

.nav-menu a {
    color: var(--white);
    font-weight: 500;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: 8px;
    transition: all var(--transition-fast);
}

.nav-menu a:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--mint);
}

.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--white);
    font-size: 1.5rem;
    cursor: pointer;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--dark-bg) 0%, var(--primary-green) 50%, var(--secondary-green) 100%);
    padding: var(--spacing-xxl) var(--spacing-md);
    color: var(--white);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1440 320"><path fill="rgba(255,255,255,0.05)" d="M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,112C672,96,768,96,864,112C960,128,1056,160,1152,160C1248,160,1344,128,1392,112L1440,96L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>') no-repeat bottom;
    background-size: cover;
    opacity: 0.3;
}

.hero-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
    align-items: center;
    position: relative;
    z-index: 1;
}

.hero-text h1 {
    color: var(--white);
    margin-bottom: var(--spacing-md);
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
    line-height: 1.8;
}

.cta-button {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    background-color: var(--mint);
    color: var(--dark-bg);
    padding: var(--spacing-md) var(--spacing-lg);
    border: none;
    border-radius: 50px;
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-medium);
    box-shadow: var(--shadow-lg);
}

.cta-button:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
    background-color: var(--pale-green);
}

.cta-button i {
    transition: transform var(--transition-medium);
}

.cta-button:hover i {
    transform: translateX(5px);
}

.hero-visual {
    position: relative;
    height: 300px;
    display: flex;
    justify-content: center;
    align-items: center;
}

.floating-icon {
    position: absolute;
    font-size: 3rem;
    color: var(--mint);
    opacity: 0.7;
    animation: float 3s ease-in-out infinite;
}

.floating-icon:nth-child(1) { top: 10%; left: 20%; }
.floating-icon:nth-child(2) { top: 30%; right: 20%; animation-delay: 0.5s; }
.floating-icon:nth-child(3) { bottom: 30%; left: 30%; animation-delay: 1s; }
.floating-icon:nth-child(4) { bottom: 10%; right: 30%; animation-delay: 1.5s; }

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

/* Quick Stats */
.quick-stats {
    max-width: 1200px;
    margin: var(--spacing-xl) auto 0;
    padding: 0 var(--spacing-md);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    position: relative;
    z-index: 1;
}

.stat-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    padding: var(--spacing-lg);
    border-radius: 16px;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.2);
    transition: all var(--transition-medium);
}

.stat-card:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.15);
}

.stat-card i {
    font-size: 2.5rem;
    color: var(--mint);
    margin-bottom: var(--spacing-sm);
}

.stat-card h3 {
    color: var(--white);
    font-size: 2rem;
    margin-bottom: var(--spacing-xs);
}

.stat-card p {
    color: var(--white);
    opacity: 0.9;
    font-size: 0.95rem;
    margin: 0;
}

/* Section Styles */
section {
    padding: var(--spacing-xxl) var(--spacing-md);
}

.section-header {
    text-align: center;
    max-width: 800px;
    margin: 0 auto var(--spacing-xl);
}

.section-header h2 {
    margin-bottom: var(--spacing-sm);
    color: var(--dark-bg);
}

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

/* Calculator Section */
.calculator-section {
    background: var(--white);
}

.calculator-container {
    max-width: 800px;
    margin: 0 auto;
}

.calculator-form {
    background: var(--light-bg);
    padding: var(--spacing-xl);
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

.form-group {
    margin-bottom: var(--spacing-lg);
}

.form-group label {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--dark-bg);
    margin-bottom: var(--spacing-sm);
}

.form-group label i {
    color: var(--primary-green);
    font-size: 1.25rem;
}

.form-group input[type="number"],
.form-group select {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    font-size: 1rem;
    font-family: var(--font-primary);
    transition: all var(--transition-fast);
    background-color: var(--white);
}

.form-group input[type="number"]:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-green);
    box-shadow: 0 0 0 3px rgba(45, 106, 79, 0.1);
}

.form-group small {
    display: block;
    margin-top: var(--spacing-xs);
    color: var(--text-light);
    font-size: 0.9rem;
}

.toggle-group {
    display: flex;
    gap: var(--spacing-sm);
    flex-wrap: wrap;
}

.toggle-option {
    flex: 1;
    min-width: 150px;
}

.toggle-option input[type="radio"] {
    display: none;
}

.toggle-option span {
    display: block;
    padding: var(--spacing-md);
    background-color: var(--white);
    border: 2px solid #e0e0e0;
    border-radius: 12px;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-fast);
    font-weight: 500;
}

.toggle-option input[type="radio"]:checked + span {
    background-color: var(--primary-green);
    color: var(--white);
    border-color: var(--primary-green);
}

.toggle-option span:hover {
    border-color: var(--primary-green);
    transform: translateY(-2px);
}

.calculate-button {
    width: 100%;
    padding: var(--spacing-md) var(--spacing-lg);
    background: linear-gradient(135deg, var(--primary-green) 0%, var(--secondary-green) 100%);
    color: var(--white);
    border: none;
    border-radius: 12px;
    font-size: 1.25rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-medium);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

.calculate-button:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

/* Results Section */
.results-section {
    background: linear-gradient(180deg, var(--white) 0%, var(--mint) 100%);
}

.results-container {
    max-width: 1200px;
    margin: 0 auto;
}

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

.result-card {
    background: var(--white);
    padding: var(--spacing-lg);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    transition: all var(--transition-medium);
}

.result-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.result-card.primary {
    background: linear-gradient(135deg, var(--primary-green) 0%, var(--secondary-green) 100%);
    color: var(--white);
    grid-column: span 2;
}

.result-card.primary .result-content h3,
.result-card.primary .result-value,
.result-card.primary .result-unit {
    color: var(--white);
}

.result-icon {
    font-size: 2.5rem;
    color: var(--primary-green);
}

.result-card.primary .result-icon {
    color: var(--mint);
}

.result-content {
    flex: 1;
}

.result-content h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: var(--spacing-xs);
}

.result-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--dark-bg);
    line-height: 1;
    margin: 0;
}

.result-unit {
    font-size: 1rem;
    color: var(--text-light);
    margin: 0;
}

/* Comparison Section */
.comparison-section {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: 20px;
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-xl);
}

.comparison-section h3 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
    color: var(--dark-bg);
}

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

.comparison-item {
    padding: var(--spacing-md);
    background: var(--light-bg);
    border-radius: 12px;
    text-align: center;
    border: 2px solid transparent;
    transition: all var(--transition-fast);
}

.comparison-item:hover {
    border-color: var(--primary-green);
    transform: translateY(-3px);
}

.comparison-item i {
    font-size: 2.5rem;
    color: var(--primary-green);
    margin-bottom: var(--spacing-sm);
}

.comparison-item .value {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--dark-bg);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.comparison-item .label {
    font-size: 0.9rem;
    color: var(--text-light);
}

/* Chart Container */
.chart-container {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: 20px;
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-xl);
}

.chart-container h3 {
    text-align: center;
    margin-bottom: var(--spacing-lg);
    color: var(--dark-bg);
}

.recalculate-button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin: var(--spacing-xl) auto 0;
    padding: var(--spacing-md) var(--spacing-xl);
    background-color: var(--primary-blue);
    color: var(--white);
    border: none;
    border-radius: 12px;
    font-size: 1.125rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-medium);
}

.recalculate-button:hover {
    background-color: var(--secondary-blue);
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

/* Learn Section */
.learn-section {
    background: var(--white);
}

.learn-content {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
}

.info-card {
    background: linear-gradient(135deg, var(--light-bg) 0%, var(--white) 100%);
    padding: var(--spacing-xl);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-medium);
}

.info-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.info-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-green) 0%, var(--secondary-green) 100%);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-md);
}

.info-icon i {
    font-size: 2rem;
    color: var(--white);
}

.info-card h3 {
    margin-bottom: var(--spacing-md);
    color: var(--dark-bg);
}

.info-card p {
    color: var(--text-dark);
    margin-bottom: var(--spacing-md);
}

.info-card ul {
    list-style: none;
    padding: 0;
}

.info-card ul li {
    padding: var(--spacing-xs) 0;
    color: var(--text-dark);
    position: relative;
    padding-left: var(--spacing-lg);
}

.info-card ul li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-green);
    font-weight: 700;
}

/* Tips Section */
.tips-section {
    background: linear-gradient(180deg, var(--mint) 0%, var(--white) 100%);
}

.tips-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.tip-card {
    background: var(--white);
    padding: var(--spacing-lg);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    transition: all var(--transition-medium);
    position: relative;
    overflow: hidden;
}

.tip-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg, var(--primary-green) 0%, var(--secondary-green) 100%);
}

.tip-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.tip-number {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-green) 0%, var(--secondary-green) 100%);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
}

.tip-card h3 {
    margin-bottom: var(--spacing-sm);
    color: var(--dark-bg);
}

.tip-card p {
    color: var(--text-dark);
    margin: 0;
}

.action-callout {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
    background: linear-gradient(135deg, var(--primary-green) 0%, var(--secondary-green) 100%);
    color: var(--white);
    padding: var(--spacing-xl);
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
}

.action-callout h3 {
    color: var(--white);
    margin-bottom: var(--spacing-md);
}

.action-callout p {
    font-size: 1.125rem;
    margin: 0;
}

/* Footer */
.footer {
    background: linear-gradient(135deg, var(--darker-bg) 0%, var(--dark-bg) 100%);
    color: var(--white);
    padding: var(--spacing-xxl) var(--spacing-md) var(--spacing-lg);
}

.footer-content {
    max-width: 120000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-xl);
    margin-bottom: var(--spacing-lg);
}

.footer-section h4 {
    color: var(--mint);
    margin-bottom: var(--spacing-md);
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.footer-section p {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.8;
}

.footer-section ul {
    list-style: none;
    padding: 0;
}

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

.footer-section ul li a {
    color: rgba(255, 255, 255, 0.8);
    transition: color var(--transition-fast);
}

.footer-section ul li a:hover {
    color: var(--mint);
}

.footer-bottom {
    max-width: 1200px;
    margin: 0 auto;
    padding-top: var(--spacing-lg);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    text-align: center;
    color: rgba(255, 255, 255, 0.6);
}

/* Responsive Design */
@media (max-width: 968px) {
    .hero-content {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-visual {
        height: 200px;
    }
    
    .result-card.primary {
        grid-column: span 1;
    }
}

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    .nav-menu {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: block;
    }
    
    .hero {
        padding: var(--spacing-xl) var(--spacing-md);
    }
    
    section {
        padding: var(--spacing-xl) var(--spacing-md);
    }
    
    .calculator-form {
        padding: var(--spacing-lg);
    }
    
    .toggle-group {
        flex-direction: column;
    }
    
    .toggle-option {
        width: 100%;
    }
    
    .results-grid {
        grid-template-columns: 1fr;
    }
    
    .comparison-grid {
        grid-template-columns: 1fr;
    }
    
    .tips-grid {
        grid-template-columns: 1fr;
    }
    
    .learn-content {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .quick-stats {
        grid-template-columns: 1fr;
    }
    
    .result-value {
        font-size: 2rem;
    }
}

/* Accessibility */
.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    margin: -1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    border: 0;
}

/* Loading Animation */
@keyframes spin {
    to { transform: rotate(360deg); }
}

.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: var(--white);
    animation: spin 0.8s linear infinite;
}

/* Smooth Scroll Padding for Fixed Header */
section[id] {
    scroll-margin-top: 80px;
}