* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --background-color: #ecf0f1;
    --danger-color: #e74c3c;
    --success-color: #2ecc71;
    --text-color: #2c3e50;
    --light-text: #7f8c8d;
    --border-color: #bdc3c7;
    --shadow: 0 2px 10px rgba(0,0,0,0.1);
    --border-radius: 12px;
    --transition: all 0.3s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    padding-bottom: 80px;
}

header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    text-align: center;
    padding: 2rem 1rem;
    margin-bottom: 2rem;
}

header h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

header p {
    opacity: 0.9;
    font-size: 1.1rem;
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.section {
    display: none;
    animation: fadeIn 0.3s ease-in;
}

.section.active {
    display: block;
}

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

/* Welcome Card */
.welcome-card {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    text-align: center;
    margin-bottom: 2rem;
}

.welcome-card h2 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.welcome-card p {
    color: var(--light-text);
    margin-bottom: 1.5rem;
}

/* Buttons */
.btn {
    background: var(--secondary-color);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    font-weight: 500;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

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

.btn-secondary {
    background: var(--light-text);
}

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

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

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    text-align: center;
    transition: var(--transition);
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-card i {
    font-size: 2rem;
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
}

.stat-card h3 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.stat-card p {
    color: var(--light-text);
    font-size: 0.9rem;
}

/* Opportunities Section */
.opportunities-section {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.opportunities-section h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 1.3rem;
}

.opportunities-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.opportunity-card {
    background: #f8f9fa;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    transition: var(--transition);
    cursor: pointer;
}

.opportunity-card:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow);
    border-color: var(--secondary-color);
}

.opportunity-card h4 {
    color: var(--primary-color);
    margin-bottom: 0.5rem;
    font-size: 1.1rem;
}

.opportunity-card .organization {
    color: var(--secondary-color);
    font-weight: 500;
    margin-bottom: 0.5rem;
}

.opportunity-card .category {
    background: var(--secondary-color);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 20px;
    font-size: 0.8rem;
    display: inline-block;
    margin-bottom: 0.5rem;
}

.opportunity-card .description {
    color: var(--light-text);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    line-height: 1.4;
}

.opportunity-card .details {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    font-size: 0.8rem;
    color: var(--light-text);
    margin-bottom: 1rem;
}

.opportunity-card .details span {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.opportunity-card .match-score {
    background: var(--success-color);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* Profile Section */
.profile-header {
    text-align: center;
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.profile-avatar {
    margin-bottom: 1rem;
}

.profile-avatar i {
    font-size: 4rem;
    color: var(--secondary-color);
}

.profile-form {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--primary-color);
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 100px;
}

.form-group select[multiple] {
    min-height: 120px;
}

/* Section Header */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.section-header h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.filters {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.filters select {
    padding: 0.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    background: white;
}

/* Create Opportunity */
.create-opportunity {
    text-align: center;
    margin-top: 2rem;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
    animation: fadeIn 0.3s ease;
}

.modal-content {
    background-color: white;
    margin: 5% auto;
    padding: 2rem;
    border-radius: var(--border-radius);
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
}

.close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    color: var(--light-text);
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
    transition: var(--transition);
}

.close:hover {
    color: var(--danger-color);
}

/* Community Section */
.community-stats {
    display: flex;
    justify-content: space-around;
    background: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 2rem;
}

.stat-item {
    text-align: center;
}

.stat-item i {
    font-size: 1.5rem;
    color: var(--secondary-color);
    margin-bottom: 0.5rem;
}

.stat-item span {
    display: block;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary-color);
}

.stat-item small {
    color: var(--light-text);
}

.posts-container {
    space-y: 1rem;
}

.post-card {
    background: white;
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 1rem;
    transition: var(--transition);
}

.post-card:hover {
    transform: translateY(-2px);
}

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

.post-title {
    color: var(--primary-color);
    font-size: 1.2rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.post-meta {
    color: var(--light-text);
    font-size: 0.9rem;
}

.post-category {
    background: var(--secondary-color);
    color: white;
    padding: 0.25rem 0.5rem;
    border-radius: 20px;
    font-size: 0.8rem;
}

.post-content {
    color: var(--text-color);
    line-height: 1.6;
    margin-bottom: 1rem;
}

.post-actions {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.post-actions button {
    background: none;
    border: none;
    color: var(--light-text);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.25rem;
    font-size: 0.9rem;
    transition: var(--transition);
}

.post-actions button:hover {
    color: var(--secondary-color);
}

.replies {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.reply {
    background: #f8f9fa;
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-bottom: 0.5rem;
}

.reply-author {
    font-weight: 500;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.reply-content {
    color: var(--text-color);
    font-size: 0.9rem;
}

.reply-form {
    margin-top: 1rem;
    display: none;
}

.reply-form.active {
    display: block;
}

.reply-form textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    resize: vertical;
    margin-bottom: 0.5rem;
}

/* FAQ Section */
.faq-section {
    background: white;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    margin: 2rem 0;
}

.faq-section h2 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    text-align: center;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 1rem;
}

.faq-question {
    width: 100%;
    background: none;
    border: none;
    padding: 1rem 0;
    text-align: left;
    font-size: 1.1rem;
    font-weight: 500;
    color: var(--primary-color);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.faq-question:hover {
    color: var(--secondary-color);
}

.faq-icon {
    font-size: 1.2rem;
    transition: var(--transition);
}

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

.faq-answer {
    padding: 0 0 1rem 0;
    color: var(--light-text);
    line-height: 1.6;
    animation: slideDown 0.3s ease;
}

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

@keyframes slideDown {
    from {
        opacity: 0;
        max-height: 0;
    }
    to {
        opacity: 1;
        max-height: 200px;
    }
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: white;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.75rem 0;
    z-index: 100;
    box-shadow: 0 -2px 10px rgba(0,0,0,0.1);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--light-text);
    transition: var(--transition);
    padding: 0.5rem;
    border-radius: var(--border-radius);
    min-width: 60px;
}

.nav-item:hover,
.nav-item.active {
    color: var(--secondary-color);
    background: rgba(52, 152, 219, 0.1);
}

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.8rem;
    font-weight: 500;
}

/* Footer */
footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 2rem 1rem;
    margin-top: 3rem;
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    header {
        padding: 1.5rem 1rem;
    }
    
    header h1 {
        font-size: 1.5rem;
    }
    
    .stats-grid {
        grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
    }
    
    .opportunities-grid {
        grid-template-columns: 1fr;
    }
    
    .section-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .filters {
        justify-content: center;
    }
    
    .modal-content {
        margin: 10% auto;
        width: 95%;
        padding: 1.5rem;
    }
    
    .community-stats {
        flex-direction: column;
        gap: 1rem;
    }
    
    .post-header {
        flex-direction: column;
        gap: 0.5rem;
    }
    
    .nav-item span {
        font-size: 0.7rem;
    }
}

@media (max-width: 480px) {
    main {
        padding: 0 0.5rem;
    }
    
    .welcome-card,
    .opportunities-section,
    .profile-form,
    .faq-section {
        padding: 1.5rem;
    }
    
    .stat-card {
        padding: 1rem;
    }
    
    .opportunity-card {
        padding: 1rem;
    }
    
    .nav-item {
        min-width: 50px;
        padding: 0.25rem;
    }
    
    .nav-item i {
        font-size: 1rem;
    }
    
    .nav-item span {
        font-size: 0.65rem;
    }
}

/* Loading States */
.loading {
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
    color: var(--light-text);
}

.loading::after {
    content: '';
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-top: 2px solid var(--secondary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-left: 0.5rem;
}

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

/* Empty States */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--light-text);
}

.empty-state i {
    font-size: 3rem;
    margin-bottom: 1rem;
    opacity: 0.5;
}

.empty-state h3 {
    margin-bottom: 0.5rem;
    color: var(--primary-color);
}

/* Success/Error Messages */
.message {
    padding: 1rem;
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.message.success {
    background: rgba(46, 204, 113, 0.1);
    color: var(--success-color);
    border: 1px solid rgba(46, 204, 113, 0.3);
}

.message.error {
    background: rgba(231, 76, 60, 0.1);
    color: var(--danger-color);
    border: 1px solid rgba(231, 76, 60, 0.3);
}

.message.info {
    background: rgba(52, 152, 219, 0.1);
    color: var(--secondary-color);
    border: 1px solid rgba(52, 152, 219, 0.3);
}