/* ========================================
   Critical Minerals Website - Main Styles
   ======================================== */

/* ===== CSS Variables ===== */
:root {
    /* Colors */
    --primary-color: #667eea;
    --primary-dark: #5568d3;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    
    --text-dark: #1a202c;
    --text-light: #718096;
    --text-white: #ffffff;
    
    --bg-light: #f7fafc;
    --bg-dark: #1a202c;
    --bg-card: #ffffff;
    
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 25px rgba(0,0,0,0.15);
    --shadow-xl: 0 20px 40px rgba(0,0,0,0.2);
    
    /* Typography */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-display: 'Playfair Display', serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ===== Reset & 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;
    overflow-x: hidden;
}

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    font-weight: 700;
}

h1 { font-size: 3.5rem; }
h2 { font-size: 2.5rem; }
h3 { font-size: 1.75rem; }
h4 { font-size: 1.25rem; }

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

ul {
    list-style: none;
}

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

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* ===== Navigation ===== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
    transition: var(--transition-normal);
}

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

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-sm);
    padding-bottom: var(--spacing-sm);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-brand i {
    font-size: 1.75rem;
}

.nav-menu {
    display: flex;
    gap: var(--spacing-md);
}

.nav-link {
    position: relative;
    padding: 0.5rem 0;
    font-weight: 500;
    color: var(--text-light);
    transition: var(--transition-fast);
}

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    transition: var(--transition-fast);
}

/* ===== Hero Section ===== */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-white);
    padding: var(--spacing-xl) 0;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><defs><pattern id="grid" width="100" height="100" patternUnits="userSpaceOnUse"><path d="M 100 0 L 0 0 0 100" fill="none" stroke="rgba(255,255,255,0.05)" stroke-width="1"/></pattern></defs><rect width="100%" height="100%" fill="url(%23grid)"/></svg>');
    opacity: 0.5;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 30% 50%, rgba(102, 126, 234, 0.3) 0%, transparent 50%),
                radial-gradient(circle at 70% 50%, rgba(118, 75, 162, 0.3) 0%, transparent 50%);
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    max-width: 900px;
}

.hero-title {
    font-family: var(--font-display);
    font-size: 4.5rem;
    margin-bottom: var(--spacing-sm);
    animation: fadeInUp 0.8s ease;
}

.hero-subtitle {
    font-size: 1.75rem;
    font-weight: 300;
    margin-bottom: var(--spacing-md);
    animation: fadeInUp 0.8s ease 0.2s backwards;
}

.hero-description {
    font-size: 1.125rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-lg);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    animation: fadeInUp 0.8s ease 0.4s backwards;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.6s backwards;
}

.btn {
    display: inline-block;
    padding: 1rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    transition: var(--transition-normal);
    cursor: pointer;
    border: 2px solid transparent;
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

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

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

.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-xl);
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.8s backwards;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1;
}

.stat-label {
    font-size: 0.875rem;
    opacity: 0.9;
    margin-top: 0.5rem;
}

.scroll-indicator {
    position: absolute;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    font-size: 2rem;
    animation: bounce 2s infinite;
    opacity: 0.7;
    cursor: pointer;
}

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

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

.section-dark {
    background: var(--bg-dark);
    color: var(--text-white);
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-lg);
}

.section-tag {
    display: inline-block;
    padding: 0.5rem 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--text-white);
    border-radius: 50px;
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: var(--spacing-sm);
}

.section-title {
    font-family: var(--font-display);
    margin-bottom: var(--spacing-sm);
}

.section-subtitle {
    font-size: 1.125rem;
    color: var(--text-light);
    max-width: 700px;
    margin: 0 auto;
}

.section-dark .section-subtitle {
    color: rgba(255,255,255,0.7);
}

/* ===== Content Grid ===== */
.content-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--spacing-lg);
    margin-top: var(--spacing-lg);
}

.content-main,
.content-sidebar {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

/* ===== Info Box ===== */
.info-box {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    display: flex;
    gap: var(--spacing-md);
}

.info-icon {
    flex-shrink: 0;
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
    color: var(--text-white);
}

.info-content h3 {
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.info-content p {
    color: var(--text-light);
    line-height: 1.7;
}

/* ===== Importance Grid ===== */
.importance-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--spacing-md);
}

.importance-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition-normal);
}

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

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

.icon-green { color: #48bb78; }
.icon-blue { color: #4299e1; }
.icon-purple { color: #9f7aea; }
.icon-red { color: #f56565; }
.icon-gray { color: #718096; }
.icon-brown { color: #a0826d; }

.importance-card h4 {
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.importance-card p {
    color: var(--text-light);
    font-size: 0.95rem;
}

/* ===== Stats Card ===== */
.stats-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.stats-card h3 {
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color);
    color: var(--text-dark);
}

.stat-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-color);
}

.stat-row:last-child {
    border-bottom: none;
}

.stat-row .stat-label {
    color: var(--text-light);
    font-size: 0.875rem;
}

.stat-row .stat-value {
    font-weight: 700;
    color: var(--primary-color);
    font-size: 1.125rem;
}

/* ===== Fact Card ===== */
.fact-card {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: var(--text-white);
    padding: var(--spacing-md);
    border-radius: 12px;
    text-align: center;
}

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

.fact-card h4 {
    margin-bottom: 0.75rem;
}

.fact-card p {
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ===== Minerals Grid ===== */
.minerals-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-md);
}

.mineral-card {
    background: var(--bg-card);
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: var(--transition-normal);
}

.mineral-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.mineral-header {
    padding: var(--spacing-md);
    color: var(--text-white);
    position: relative;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.mineral-header i {
    font-size: 2rem;
}

.mineral-header h3 {
    flex: 1;
    margin-left: var(--spacing-sm);
}

.mineral-symbol {
    font-size: 1.5rem;
    font-weight: 700;
    opacity: 0.7;
}

.mineral-body {
    padding: var(--spacing-md);
}

.mineral-desc {
    color: var(--text-light);
    margin-bottom: var(--spacing-md);
    line-height: 1.6;
}

.mineral-stats {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-bottom: var(--spacing-md);
}

.mineral-stat {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.mineral-stat .label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    color: var(--text-light);
    font-weight: 600;
}

.mineral-stat .value {
    font-weight: 600;
    color: var(--text-dark);
}

.mineral-applications {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.mineral-applications .tag,
.mineral-tags span {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--bg-light);
    color: var(--text-dark);
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 500;
}

.mineral-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.list-item {
    padding: 0.5rem;
    background: var(--bg-light);
    border-radius: 6px;
    font-size: 0.9rem;
    color: var(--text-dark);
}

.list-item strong {
    color: var(--primary-color);
}

/* ===== Applications Section ===== */
.applications-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.application-section {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.application-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-md);
    border-bottom: 2px solid var(--border-color);
}

.app-icon {
    width: 70px;
    height: 70px;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: var(--text-white);
    flex-shrink: 0;
}

.application-header h3 {
    font-size: 1.75rem;
    margin-bottom: 0.25rem;
}

.application-header p {
    color: var(--text-light);
    font-size: 0.95rem;
}

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

.app-card {
    background: var(--bg-light);
    padding: var(--spacing-md);
    border-radius: 12px;
    transition: var(--transition-normal);
}

.app-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.app-card h4 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.app-card h4 i {
    color: var(--primary-color);
}

.app-card p {
    color: var(--text-light);
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
    font-size: 0.95rem;
}

.mineral-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

/* ===== Charts ===== */
.chart-container {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.section-dark .chart-container {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
}

/* ===== Supply Chain Section ===== */
.supply-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.supply-section h3 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: var(--spacing-md);
    font-size: 1.75rem;
}

.lead-text {
    font-size: 1.125rem;
    line-height: 1.7;
    color: rgba(255,255,255,0.85);
    margin-bottom: var(--spacing-lg);
    max-width: 900px;
}

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

.concentration-card {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    border: 1px solid rgba(255,255,255,0.1);
}

.country-flag {
    font-size: 3rem;
    text-align: center;
    margin-bottom: var(--spacing-sm);
}

.concentration-card h4 {
    text-align: center;
    margin-bottom: var(--spacing-md);
    font-size: 1.25rem;
}

.dominance-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.dominance-item span {
    display: block;
    font-size: 0.875rem;
    margin-bottom: 0.5rem;
    opacity: 0.9;
}

.progress-bar {
    height: 30px;
    background: rgba(255,255,255,0.1);
    border-radius: 15px;
    overflow: hidden;
    position: relative;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 0.75rem;
    font-weight: 700;
    font-size: 0.875rem;
    transition: width 1s ease;
}

/* ===== Challenges Grid ===== */
.challenges-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.challenge-card {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    text-align: center;
    border: 1px solid rgba(255,255,255,0.1);
    transition: var(--transition-normal);
}

.challenge-card:hover {
    transform: translateY(-5px);
    background: rgba(255,255,255,0.08);
}

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

.challenge-card h4 {
    margin-bottom: 0.5rem;
}

.challenge-card p {
    font-size: 0.9rem;
    opacity: 0.85;
    line-height: 1.6;
}

/* ===== Response Section ===== */
.response-section {
    margin-top: var(--spacing-xl);
}

.response-section h3 {
    margin-bottom: var(--spacing-lg);
}

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

.response-card {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    border: 1px solid rgba(255,255,255,0.1);
    position: relative;
    padding-top: 3.5rem;
}

.response-number {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.125rem;
}

.response-card h4 {
    margin-bottom: 0.75rem;
}

.response-card p {
    font-size: 0.95rem;
    opacity: 0.85;
    margin-bottom: var(--spacing-sm);
    line-height: 1.6;
}

.response-examples {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.example {
    padding: 0.25rem 0.75rem;
    background: rgba(255,255,255,0.1);
    border-radius: 50px;
    font-size: 0.8rem;
}

/* ===== Sustainability Section ===== */
.sustainability-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.env-challenges h3,
.recycling-section h3,
.solutions-section h3 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: var(--spacing-md);
    font-size: 1.75rem;
}

.challenge-grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
}

.env-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.env-card i {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
}

.env-card h4 {
    margin-bottom: 0.75rem;
    color: var(--text-dark);
}

.env-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-sm);
}

.impact-meter {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-top: var(--spacing-sm);
}

.impact-meter span {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-light);
}

.meter {
    padding: 0.25rem 0.75rem;
    border-radius: 50px;
    font-size: 0.8rem;
    font-weight: 600;
}

.meter.high {
    background: #fee;
    color: #c53030;
}

.meter.medium {
    background: #fef5e7;
    color: #d97706;
}

/* ===== Recycling Stats ===== */
.recycling-stats-grid {
    display: grid;
    gap: var(--spacing-md);
}

.recycling-stat-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    display: flex;
    gap: var(--spacing-md);
}

.stat-icon {
    width: 70px;
    height: 70px;
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: var(--text-white);
    flex-shrink: 0;
}

.stat-content {
    flex: 1;
}

.stat-content h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-dark);
}

.stat-bar {
    margin-bottom: 1rem;
}

.bar-label {
    font-size: 0.875rem;
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.bar {
    height: 30px;
    background: var(--bg-light);
    border-radius: 15px;
    overflow: hidden;
}

.bar-fill {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: flex-end;
    padding-right: 0.75rem;
    color: var(--text-white);
    font-weight: 700;
    font-size: 0.875rem;
    transition: width 1s ease;
}

.stat-note {
    font-size: 0.875rem;
    color: var(--text-light);
    font-style: italic;
}

/* ===== Solutions Grid ===== */
.solutions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
}

.solution-card {
    background: var(--bg-card);
    padding: var(--spacing-md);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}

.solution-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
    color: var(--text-white);
    margin-bottom: var(--spacing-sm);
}

.solution-card h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-dark);
}

.solution-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.solution-list li {
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.6;
}

.solution-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: 700;
}

/* ===== Circular Economy ===== */
.circular-economy {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    padding: var(--spacing-lg);
    border-radius: 16px;
    color: var(--text-white);
}

.circular-economy h3 {
    color: var(--text-white);
}

.circular-diagram {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
    margin-top: var(--spacing-lg);
}

.circular-step {
    background: rgba(255,255,255,0.15);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    text-align: center;
    flex: 0 0 200px;
    position: relative;
}

.step-number {
    position: absolute;
    top: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 35px;
    height: 35px;
    background: var(--text-white);
    color: var(--primary-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.125rem;
}

.circular-step i {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
}

.circular-step h4 {
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.circular-step p {
    font-size: 0.875rem;
    opacity: 0.9;
}

.circular-arrow {
    font-size: 2rem;
    font-weight: 700;
    opacity: 0.7;
}

.circular-arrow-back {
    flex-basis: 100%;
    text-align: center;
    font-size: 3rem;
}

/* ===== Future Section ===== */
.future-content {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

.trends-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: var(--spacing-md);
}

.trend-card {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    border: 1px solid rgba(255,255,255,0.1);
}

.trend-card.featured {
    grid-column: span 2;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.2), rgba(118, 75, 162, 0.2));
}

.trend-icon {
    width: 60px;
    height: 60px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
    margin-bottom: var(--spacing-sm);
}

.trend-card h3 {
    margin-bottom: 0.75rem;
}

.trend-stat {
    font-size: 1.125rem;
    color: var(--accent-color);
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

.trend-card ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.trend-card li {
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.95rem;
    opacity: 0.9;
    line-height: 1.6;
}

.trend-card li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent-color);
}

.trend-card li strong {
    color: var(--text-white);
}

/* ===== Timeline ===== */
.timeline-section h3 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: var(--spacing-lg);
}

.timeline {
    position: relative;
    padding-left: var(--spacing-lg);
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(180deg, var(--primary-color), var(--accent-color));
}

.timeline-item {
    position: relative;
    margin-bottom: var(--spacing-lg);
}

.timeline-year {
    position: absolute;
    left: -60px;
    top: 0;
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.875rem;
    z-index: 2;
}

.timeline-content {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    margin-left: var(--spacing-md);
}

.timeline-content h4 {
    margin-bottom: 0.75rem;
    color: var(--accent-color);
}

.timeline-content ul {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.timeline-content li {
    padding-left: 1.5rem;
    position: relative;
    font-size: 0.95rem;
    opacity: 0.9;
    line-height: 1.6;
}

.timeline-content li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--accent-color);
    font-size: 1.5rem;
    line-height: 1;
}

/* ===== Challenges & Opportunities ===== */
.challenges-opportunities {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.co-column h3 {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: var(--spacing-md);
}

.co-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.co-item {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    padding: var(--spacing-md);
    border-radius: 12px;
    display: flex;
    gap: var(--spacing-sm);
    border-left: 3px solid;
}

.co-item.challenge {
    border-color: #f56565;
}

.co-item.opportunity {
    border-color: #48bb78;
}

.co-number {
    flex-shrink: 0;
    width: 30px;
    height: 30px;
    background: rgba(255,255,255,0.1);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 0.875rem;
}

.co-item h4 {
    margin-bottom: 0.5rem;
    font-size: 1.125rem;
}

.co-item p {
    font-size: 0.9rem;
    opacity: 0.85;
    line-height: 1.6;
}

/* ===== CTA Section ===== */
.cta-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: var(--text-white);
    padding: var(--spacing-xl) 0;
    text-align: center;
}

.cta-content {
    max-width: 900px;
    margin: 0 auto;
}

.cta-content h2 {
    font-family: var(--font-display);
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
}

.cta-content p {
    font-size: 1.125rem;
    line-height: 1.7;
    opacity: 0.95;
    margin-bottom: var(--spacing-lg);
}

.cta-stats {
    display: flex;
    justify-content: center;
    gap: var(--spacing-xl);
    flex-wrap: wrap;
}

.cta-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.cta-stat strong {
    font-size: 2.5rem;
    font-weight: 800;
    display: block;
    margin-bottom: 0.5rem;
}

.cta-stat span {
    font-size: 0.95rem;
    opacity: 0.9;
}

/* ===== Footer ===== */
.footer {
    background: var(--bg-dark);
    color: rgba(255,255,255,0.8);
    padding: var(--spacing-lg) 0 var(--spacing-md);
}

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.footer-brand p {
    margin-top: var(--spacing-sm);
    opacity: 0.8;
    line-height: 1.6;
}

.footer-links h4 {
    margin-bottom: var(--spacing-sm);
    color: var(--text-white);
}

.footer-links ul {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.footer-links a {
    opacity: 0.8;
    transition: var(--transition-fast);
}

.footer-links a:hover {
    opacity: 1;
    color: var(--accent-color);
}

.footer-bottom {
    padding-top: var(--spacing-md);
    border-top: 1px solid rgba(255,255,255,0.1);
    text-align: center;
}

.footer-bottom p {
    opacity: 0.7;
    font-size: 0.875rem;
    margin-bottom: 0.25rem;
}

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

@keyframes bounce {
    0%, 100% {
        transform: translateX(-50%) translateY(0);
    }
    50% {
        transform: translateX(-50%) translateY(-10px);
    }
}

/* ===== Responsive Design ===== */
@media (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .trend-card.featured {
        grid-column: span 1;
    }
    
    .challenges-opportunities {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 768px) {
    html {
        font-size: 14px;
    }
    
    h1 { font-size: 2.5rem; }
    h2 { font-size: 2rem; }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        height: calc(100vh - 70px);
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(10px);
        flex-direction: column;
        padding: var(--spacing-md);
        gap: 0;
        transition: left var(--transition-normal);
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-link {
        padding: var(--spacing-sm) 0;
        border-bottom: 1px solid var(--border-color);
    }
    
    .nav-toggle {
        display: flex;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .hero-stats {
        gap: var(--spacing-md);
    }
    
    .stat-number {
        font-size: 2rem;
    }
    
    .importance-grid {
        grid-template-columns: 1fr;
    }
    
    .minerals-grid {
        grid-template-columns: 1fr;
    }
    
    .application-grid {
        grid-template-columns: 1fr;
    }
    
    .concentration-grid {
        grid-template-columns: 1fr;
    }
    
    .challenge-grid-2 {
        grid-template-columns: 1fr;
    }
    
    .solutions-grid {
        grid-template-columns: 1fr;
    }
    
    .trends-grid {
        grid-template-columns: 1fr;
    }
    
    .circular-diagram {
        flex-direction: column;
    }
    
    .circular-arrow {
        transform: rotate(90deg);
    }
    
    .circular-arrow-back {
        transform: rotate(0);
    }
    
    .timeline {
        padding-left: var(--spacing-md);
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-year {
        left: -10px;
        width: 35px;
        height: 35px;
        font-size: 0.75rem;
    }
    
    .cta-content h2 {
        font-size: 2rem;
    }
    
    .cta-stats {
        gap: var(--spacing-md);
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

/* ===== Citations & References Styling ===== */

/* Inline citations */
sup.cite {
    font-size: 0.7em;
    font-weight: 600;
    color: var(--primary-color);
    margin-left: 2px;
    cursor: pointer;
    transition: var(--transition-fast);
}

sup.cite:hover {
    color: var(--secondary-color);
    text-decoration: underline;
}

/* References Section */
.references-section {
    background: var(--bg-light);
}

.references-content {
    max-width: 1000px;
    margin: 0 auto;
}

.references-intro {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1), rgba(118, 75, 162, 0.1));
    padding: var(--spacing-md);
    border-radius: 12px;
    border-left: 4px solid var(--primary-color);
    margin-bottom: var(--spacing-lg);
}

.references-intro p {
    margin: 0;
    line-height: 1.7;
    color: var(--text-dark);
}

.references-intro strong {
    color: var(--primary-color);
}

.references-list {
    background: var(--bg-card);
    padding: var(--spacing-lg);
    border-radius: 16px;
    box-shadow: var(--shadow-md);
}

.ref-category {
    font-family: var(--font-display);
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--border-color);
}

.reference-item {
    display: flex;
    gap: var(--spacing-sm);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    background: var(--bg-light);
    border-radius: 8px;
    border-left: 3px solid var(--primary-color);
    transition: var(--transition-normal);
}

.reference-item:hover {
    box-shadow: var(--shadow-sm);
    transform: translateX(5px);
}

.ref-number {
    flex-shrink: 0;
    font-weight: 700;
    color: var(--primary-color);
    font-size: 1rem;
    min-width: 40px;
}

.ref-content {
    flex: 1;
}

.ref-authors {
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.25rem;
    line-height: 1.5;
}

.ref-title {
    font-weight: 500;
    color: var(--text-dark);
    margin-bottom: 0.25rem;
    line-height: 1.5;
}

.ref-source {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-bottom: 0.25rem;
    line-height: 1.5;
    font-style: italic;
}

.ref-link {
    margin-top: 0.5rem;
}

.ref-link a {
    color: var(--primary-color);
    font-size: 0.85rem;
    word-break: break-all;
    text-decoration: none;
    transition: var(--transition-fast);
}

.ref-link a:hover {
    color: var(--secondary-color);
    text-decoration: underline;
}

.ref-doi {
    font-size: 0.9rem;
    color: var(--text-light);
    font-family: 'Courier New', monospace;
    margin-top: 0.25rem;
}

.ref-note {
    margin-top: 0.5rem;
    font-size: 0.85rem;
    color: var(--text-light);
    padding-left: 1rem;
    border-left: 2px solid var(--border-color);
    line-height: 1.6;
}

.ref-note em {
    font-style: italic;
}

.references-disclaimer {
    background: linear-gradient(135deg, rgba(245, 87, 108, 0.1), rgba(250, 112, 154, 0.1));
    padding: var(--spacing-md);
    border-radius: 12px;
    border-left: 4px solid #f5576c;
    margin-top: var(--spacing-lg);
}

.references-disclaimer h4 {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: #f5576c;
    margin-bottom: var(--spacing-sm);
}

.references-disclaimer h4 i {
    font-size: 1.25rem;
}

.references-disclaimer p {
    color: var(--text-dark);
    line-height: 1.7;
    margin-bottom: 0;
}

/* Academic formatting for citations */
.stat-label sup.cite,
.mineral-stat .value sup.cite {
    font-size: 0.65em;
}

/* Responsive adjustments for references */
@media (max-width: 768px) {
    .reference-item {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .ref-number {
        min-width: auto;
    }
    
    .ref-link a {
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .info-box {
        flex-direction: column;
    }
    
    .recycling-stat-card {
        flex-direction: column;
    }
}