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

:root {
    /* Color Palette */
    --primary-color: #7868E6;
    --secondary-color: #B8B5FF;
    --accent-color: #FFB4B4;
    --background-light: #EDEEF7;
    --background-accent: #E4FBFF;
    --text-dark: #2c2c2c;
    --text-light: #666;
    --white: #ffffff;
    --shadow: rgba(120, 104, 230, 0.1);
    --border: rgba(120, 104, 230, 0.2);
    
    /* Typography */
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(120, 104, 230, 0.1);
    --shadow-md: 0 4px 6px rgba(120, 104, 230, 0.1);
    --shadow-lg: 0 10px 15px rgba(120, 104, 230, 0.1);
    
    /* Transitions */
    --transition: all 0.3s ease;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--text-dark);
    background: linear-gradient(135deg, var(--background-light) 0%, var(--background-accent) 100%);
    min-height: 100vh;
}

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

/* Header */
.header {
    background: var(--white);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 0;
    z-index: 100;
    border-bottom: 3px solid var(--primary-color);
}

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

.logo {
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--primary-color);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

/* Navigation */
.nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    font-size: var(--font-size-lg);
    color: var(--primary-color);
    cursor: pointer;
    padding: var(--spacing-sm);
}

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

.nav-link {
    background: none;
    border: none;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-lg);
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    font-size: var(--font-size-sm);
    white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
    background: var(--secondary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

/* Language Toggle */
.language-toggle {
    display: flex;
    align-items: center;
}

/* Buttons */
.btn-primary,
.btn-secondary {
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-lg);
    border: none;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-sm);
    position: relative;
    overflow: hidden;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: var(--white);
    box-shadow: var(--shadow-md);
}

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

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

.btn-secondary:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
}

/* Main Content */
.main {
    flex: 1;
    padding: var(--spacing-xl) 0;
}

/* Pages */
.page {
    display: none;
    animation: fadeIn 0.5s ease-in-out;
}

.page.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Page Header */
.page-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.page-header h2 {
    font-size: var(--font-size-3xl);
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    font-weight: 700;
}

.page-header p {
    font-size: var(--font-size-lg);
    color: var(--text-light);
    max-width: 600px;
    margin: 0 auto;
}

/* Welcome Page */
.welcome-hero {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    padding: var(--spacing-2xl) 0;
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: var(--spacing-md);
    line-height: 1.2;
}

.hero-subtitle {
    font-size: var(--font-size-xl);
    color: var(--text-light);
    margin-bottom: var(--spacing-xl);
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}

.welcome-actions {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
}

.feature-card {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow-lg);
    transition: var(--transition);
    border: 3px solid transparent;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--secondary-color), var(--accent-color));
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--secondary-color);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.feature-card h3 {
    font-size: var(--font-size-xl);
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
}

.feature-card p {
    color: var(--text-light);
    line-height: 1.6;
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.stat-card {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    text-align: center;
    box-shadow: var(--shadow-md);
    border: 2px solid var(--secondary-color);
    transition: var(--transition);
}

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

.stat-icon {
    font-size: 2.5rem;
    margin-bottom: var(--spacing-sm);
    display: block;
}

.stat-number {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    color: var(--primary-color);
    display: block;
    margin-bottom: var(--spacing-xs);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    font-weight: 500;
}

/* Dashboard Content */
.dashboard-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: var(--spacing-xl);
}

.skills-available,
.recent-activity {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.skills-available h3,
.recent-activity h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-lg);
    font-size: var(--font-size-xl);
    font-weight: 600;
}

/* Skills List */
.skills-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.skill-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--background-light);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--primary-color);
}

.skill-info h4 {
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
}

.skill-info p {
    color: var(--text-light);
    font-size: var(--font-size-sm);
}

.skill-level {
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 600;
    text-transform: uppercase;
}

.skill-level.beginner {
    background: #e3f2fd;
    color: #1976d2;
}

.skill-level.intermediate {
    background: #fff3e0;
    color: #f57c00;
}

.skill-level.advanced {
    background: #e8f5e8;
    color: #388e3c;
}

/* Activity List */
.activity-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.activity-item {
    padding: var(--spacing-sm);
    background: var(--background-light);
    border-radius: var(--radius-md);
    font-size: var(--font-size-sm);
    color: var(--text-light);
}

/* Forms */
.profile-form,
.exchange-form,
.project-form {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    margin-bottom: var(--spacing-xl);
}

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

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-sm);
    font-weight: 600;
    color: var(--primary-color);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: var(--spacing-md);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    transition: var(--transition);
    background: var(--white);
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(120, 104, 230, 0.1);
}

.form-actions {
    margin-top: var(--spacing-xl);
    text-align: center;
}

/* Skills and Interests */
.skills-section,
.interests-section {
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-xl);
    border-top: 2px solid var(--background-light);
}

.skill-input-group,
.interest-input-group {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.skill-input-group input,
.interest-input-group input {
    flex: 1;
}

.skills-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-sm);
}

.skill-tag,
.interest-tag {
    background: var(--secondary-color);
    color: var(--primary-color);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-lg);
    font-size: var(--font-size-sm);
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.remove-tag {
    background: none;
    border: none;
    color: var(--primary-color);
    cursor: pointer;
    font-weight: bold;
}

/* Time Credits */
.time-credits {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    margin-top: var(--spacing-xl);
}

.time-credits h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

.credits-display {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-lg);
    text-align: center;
}

.credits-earned,
.credits-spent,
.credits-balance {
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
}

.credits-earned {
    background: linear-gradient(135deg, #e8f5e8, #c8e6c9);
}

.credits-spent {
    background: linear-gradient(135deg, #ffebee, #ffcdd2);
}

.credits-balance {
    background: linear-gradient(135deg, var(--background-accent), var(--secondary-color));
}

.credits-number {
    font-size: var(--font-size-2xl);
    font-weight: 800;
    color: var(--primary-color);
    display: block;
}

.credits-label {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    font-weight: 500;
}

/* Tabs */
.exchange-tabs,
.projects-tabs {
    display: flex;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    border-bottom: 2px solid var(--background-light);
}

.tab-btn {
    background: none;
    border: none;
    padding: var(--spacing-md) var(--spacing-lg);
    cursor: pointer;
    font-weight: 600;
    color: var(--text-light);
    border-bottom: 3px solid transparent;
    transition: var(--transition);
}

.tab-btn.active,
.tab-btn:hover {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

/* Filters */
.filters {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.filters input,
.filters select {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    background: var(--white);
}

/* Opportunities and Projects Lists */
.opportunities-list,
.exchanges-list,
.projects-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.opportunity-card,
.exchange-card,
.project-card {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
    border-left: 5px solid var(--primary-color);
    transition: var(--transition);
}

.opportunity-card:hover,
.exchange-card:hover,
.project-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-lg);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.card-meta {
    font-size: var(--font-size-sm);
    color: var(--text-light);
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.card-description {
    margin-bottom: var(--spacing-md);
    color: var(--text-dark);
    line-height: 1.6;
}

.card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: var(--spacing-md);
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--background-light);
}

.card-actions {
    display: flex;
    gap: var(--spacing-sm);
}

/* Recognition Page */
.recognition-content {
    display: grid;
    gap: var(--spacing-xl);
}

.leaderboard,
.achievements,
.community-heroes {
    background: var(--white);
    padding: var(--spacing-xl);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.leaderboard h3,
.achievements h3,
.community-heroes h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-lg);
    text-align: center;
    font-size: var(--font-size-xl);
}

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

.leaderboard-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--background-light);
    border-radius: var(--radius-md);
}

.rank-position {
    font-size: var(--font-size-xl);
    font-weight: 800;
    color: var(--primary-color);
    min-width: 40px;
    text-align: center;
}

.user-info {
    flex: 1;
}

.user-name {
    font-weight: 600;
    color: var(--text-dark);
}

.user-points {
    font-size: var(--font-size-sm);
    color: var(--text-light);
}

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

.achievement-card {
    text-align: center;
    padding: var(--spacing-lg);
    background: var(--background-light);
    border-radius: var(--radius-md);
    transition: var(--transition);
}

.achievement-card:hover {
    transform: translateY(-3px);
    background: var(--secondary-color);
}

.achievement-icon {
    font-size: 3rem;
    margin-bottom: var(--spacing-sm);
    display: block;
}

.achievement-title {
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: var(--spacing-xs);
}

.achievement-description {
    font-size: var(--font-size-sm);
    color: var(--text-light);
}

/* Heroes List */
.heroes-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.hero-card {
    text-align: center;
    padding: var(--spacing-xl);
    background: linear-gradient(135deg, var(--background-accent), var(--secondary-color));
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-md);
}

.hero-avatar {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    display: block;
}

.hero-name {
    font-size: var(--font-size-xl);
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.hero-contribution {
    color: var(--text-light);
    font-style: italic;
}

/* FAQ */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-item {
    background: var(--white);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-md);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    background: none;
    border: none;
    padding: var(--spacing-lg);
    text-align: left;
    cursor: pointer;
    font-weight: 600;
    color: var(--primary-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    background: var(--background-light);
}

.faq-question[aria-expanded="true"] {
    background: var(--secondary-color);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
}

.faq-icon {
    font-size: var(--font-size-xl);
    font-weight: bold;
    transition: var(--transition);
}

.faq-answer {
    padding: 0 var(--spacing-lg) var(--spacing-lg);
    color: var(--text-dark);
    line-height: 1.6;
    animation: slideDown 0.3s ease-out;
}

.faq-answer[hidden] {
    display: none;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Footer */
.footer {
    background: var(--primary-color);
    color: var(--white);
    text-align: center;
    padding: var(--spacing-xl) 0;
    margin-top: var(--spacing-2xl);
}

.footer p {
    margin: 0;
    font-size: var(--font-size-sm);
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

.loading-overlay.show {
    opacity: 1;
    visibility: visible;
}

.loading-spinner {
    text-align: center;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--background-light);
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto var(--spacing-md);
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 var(--spacing-sm);
    }
    
    .header-content {
        flex-wrap: wrap;
        gap: var(--spacing-md);
    }
    
    .nav-toggle {
        display: block;
        order: 3;
    }
    
    .nav {
        order: 4;
        width: 100%;
        position: relative;
    }
    
    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        flex-direction: column;
        box-shadow: var(--shadow-lg);
        border-radius: var(--radius-md);
        padding: var(--spacing-md);
        transform: translateY(-10px);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
        z-index: 50;
    }
    
    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }
    
    .nav-menu li {
        width: 100%;
    }
    
    .nav-link {
        width: 100%;
        text-align: center;
        padding: var(--spacing-md);
    }
    
    .language-toggle {
        order: 2;
    }
    
    .welcome-actions {
        flex-direction: column;
        align-items: center;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    
    .dashboard-content {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .credits-display {
        grid-template-columns: 1fr;
    }
    
    .exchange-tabs,
    .projects-tabs {
        flex-wrap: wrap;
        justify-content: center;
    }
    
    .filters {
        flex-direction: column;
    }
    
    .card-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .card-footer {
        flex-direction: column;
        gap: var(--spacing-md);
        align-items: stretch;
    }
    
    .card-actions {
        justify-content: center;
    }
    
    .skill-input-group,
    .interest-input-group {
        flex-direction: column;
    }
    
    .achievements-grid {
        grid-template-columns: 1fr;
    }
    
    .heroes-list {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-subtitle {
        font-size: var(--font-size-lg);
    }
    
    .page-header h2 {
        font-size: var(--font-size-2xl);
    }
    
    .feature-card,
    .stat-card,
    .profile-form,
    .exchange-form,
    .project-form {
        padding: var(--spacing-lg);
    }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for keyboard navigation */
button:focus,
input:focus,
textarea:focus,
select:focus,
.nav-link:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    :root {
        --shadow: rgba(0, 0, 0, 0.3);
        --border: rgba(0, 0, 0, 0.5);
    }
}

/* Print styles */
@media print {
    .header,
    .footer,
    .nav,
    .btn-primary,
    .btn-secondary,
    .loading-overlay {
        display: none !important;
    }
    
    .main {
        padding: 0;
    }
    
    .page {
        display: block !important;
        page-break-after: always;
    }
    
    .container {
        max-width: none;
        padding: 0;
    }
}