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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f5f5f5;
    color: #333;
}

.screen {
    display: none;
}

.screen.active {
    display: flex;
    min-height: 100vh;
}

/* Login & Register Screens */
#login-screen, #register-screen {
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.login-container {
    background: white;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
    width: 100%;
    max-width: 400px;
}

.login-container h1 {
    margin-bottom: 30px;
    color: #667eea;
    text-align: center;
}

/* Form Styles */
.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 600;
    color: #555;
}

.form-group input, 
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 14px;
    transition: border-color 0.3s;
}

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

/* Button Styles */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s;
    margin-right: 10px;
}

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

.btn-primary:hover {
    background-color: #5568d3;
}

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

.btn-secondary:hover {
    background-color: #5a6268;
}

.btn-success {
    background-color: #28a745;
    color: white;
}

.btn-success:hover {
    background-color: #218838;
}

.btn-danger {
    background-color: #dc3545;
    color: white;
}

.btn-danger:hover {
    background-color: #c82333;
}

.btn-warning {
    background-color: #ffc107;
    color: #333;
}

.btn-warning:hover {
    background-color: #e0a800;
}

.btn-info {
    background-color: #17a2b8;
    color: white;
}

.btn-info:hover {
    background-color: #138496;
}

/* Dashboard Layout */
.dashboard-container {
    display: flex;
    min-height: 100vh;
}

/* Sidebar */
.sidebar {
    width: 250px;
    background-color: #2c3e50;
    color: white;
    display: flex;
    flex-direction: column;
    position: fixed;
    height: 100vh;
    overflow-y: auto;
}

.sidebar .logo {
    padding: 20px;
    background-color: #1a252f;
    text-align: center;
}

.sidebar .logo h2 {
    color: #667eea;
}

.nav-menu {
    flex: 1;
    padding: 20px 0;
}

.nav-menu ul {
    list-style: none;
}

.nav-menu li {
    margin-bottom: 5px;
}

.nav-link {
    display: block;
    padding: 12px 20px;
    color: #ecf0f1;
    text-decoration: none;
    transition: background-color 0.3s;
}

.nav-link:hover {
    background-color: #34495e;
}

.nav-link.active {
    background-color: #667eea;
}

#logout-btn {
    margin: 20px;
}

/* Main Content */
.main-content {
    flex: 1;
    margin-left: 250px;
    background-color: #f5f5f5;
}

.header {
    background-color: white;
    padding: 20px 30px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header h1 {
    color: #2c3e50;
    font-size: 24px;
}

.user-info {
    color: #666;
}

.content {
    padding: 30px;
}

/* Dashboard Stats */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 30px;
}

.stat-card {
    background: white;
    padding: 25px;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    text-align: center;
}

.stat-card h3 {
    color: #666;
    font-size: 14px;
    margin-bottom: 10px;
}

.stat-number {
    font-size: 36px;
    font-weight: bold;
    color: #667eea;
}

/* Table Styles */
.table-container {
    background: white;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    overflow-x: auto;
    margin-top: 20px;
}

table {
    width: 100%;
    border-collapse: collapse;
}

table th {
    background-color: #667eea;
    color: white;
    padding: 12px;
    text-align: left;
    font-weight: 600;
}

table td {
    padding: 12px;
    border-bottom: 1px solid #ddd;
}

table tr:hover {
    background-color: #f9f9f9;
}

table tr:last-child td {
    border-bottom: none;
}

/* Form Container */
.form-container {
    background: white;
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    max-width: 800px;
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

/* Alert Messages */
.alert {
    padding: 15px;
    border-radius: 5px;
    margin-bottom: 20px;
}

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

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

.alert-info {
    background-color: #d1ecf1;
    color: #0c5460;
    border: 1px solid #bee5eb;
}

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

.modal.active {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background-color: white;
    padding: 30px;
    border-radius: 10px;
    max-width: 500px;
    width: 90%;
}

.modal-header {
    margin-bottom: 20px;
}

.modal-footer {
    margin-top: 20px;
    text-align: right;
}

/* Responsive Design */
@media (max-width: 768px) {
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .table-container {
        overflow-x: scroll;
    }
}

/* Loading Spinner */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid #f3f3f3;
    border-top: 3px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

/* Empty State */
.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: #999;
}

.empty-state h3 {
    margin-bottom: 10px;
    color: #666;
}

/* Action Buttons in Table */
.action-buttons {
    display: flex;
    gap: 5px;
}

.action-buttons .btn {
    padding: 5px 10px;
    font-size: 12px;
    margin: 0;
}