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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: #f5f5f5;
    color: #333;
    line-height: 1.6;
}

a {
    text-decoration: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 1rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    text-decoration: none;
    color: white;
}

.nav {
    display: flex;
    gap: 20px;
}

.nav a {
    color: white;
    text-decoration: none;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    transition: background 0.3s;
}

.nav a:hover {
    background: rgba(255,255,255,0.2);
}

.nav a.active {
    background: rgba(255,255,255,0.3);
}

.card {
    background: white;
    border-radius: 10px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 1rem;
    transition: all 0.3s;
}

.btn-primary {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: #6c757d;
    color: white;
}

.btn-outline {
    background: transparent;
    border: 2px solid #667eea;
    color: #667eea;
}

.btn-outline:hover {
    background: #667eea;
    color: white;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: #667eea;
}

.hidden {
    display: none !important;
}

.tag {
    display: inline-block;
    background: #e9ecef;
    padding: 5px 10px;
    border-radius: 15px;
    margin: 2px;
    font-size: 0.85rem;
}

.demand-card {
    border-left: 4px solid #667eea;
}

.demand-card.supply {
    border-left-color: #28a745;
}

.demand-card.connection {
    border-left-color: #ffc107;
}

.demand-card .demand-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
}

.demand-card .demand-type {
    background: #667eea;
    color: white;
    padding: 3px 10px;
    border-radius: 3px;
    font-size: 0.8rem;
}

.demand-card.supply .demand-type {
    background: #28a745;
}

.demand-card.connection .demand-type {
    background: #ffc107;
}

.user-card {
    display: flex;
    align-items: center;
    gap: 15px;
}

.user-card .avatar {
    width: 60px;
    height: 60px;
    border-radius: 50%;
    object-fit: cover;
}

.user-card .user-info {
    flex: 1;
}

.message-list {
    max-height: 400px;
    overflow-y: auto;
}

.message-item {
    padding: 10px;
    margin-bottom: 10px;
    border-radius: 5px;
}

.message-item.sent {
    background: #667eea;
    color: white;
    margin-left: 20%;
}

.message-item.received {
    background: #e9ecef;
    margin-right: 20%;
}

.loading {
    text-align: center;
    padding: 20px;
}

.spinner {
    border: 3px solid #f3f3f3;
    border-top: 3px solid #667eea;
    border-radius: 50%;
    width: 30px;
    height: 30px;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

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

.alert {
    padding: 10px 15px;
    border-radius: 5px;
    margin-bottom: 15px;
}

.alert-success {
    background: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.modal-content {
    background: white;
    padding: 20px;
    border-radius: 10px;
    max-width: 500px;
    width: 90%;
    max-height: 80vh;
    overflow-y: auto;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.stat-card {
    background: white;
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

.stat-card .stat-value {
    font-size: 2rem;
    font-weight: bold;
    color: #667eea;
}

.stat-card .stat-label {
    color: #6c757d;
    margin-top: 5px;
}