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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}

.screen {
    display: none;
}

.screen.active {
    display: block;
}

/* Login Screen */
.login-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.store-logo {
    text-align: center;
    margin-bottom: 2rem;
    color: white;
}

.store-logo h1 {
    font-size: 3rem;
    margin-bottom: 0.5rem;
}

.store-logo p {
    font-size: 1.2rem;
    opacity: 0.9;
}

.login-form {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    width: 100%;
    max-width: 400px;
}

.login-form h2 {
    text-align: center;
    margin-bottom: 1.5rem;
    color: #333;
}

.form-group {
    margin-bottom: 1rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: #555;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
    transition: border-color 0.3s;
}

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

.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 5px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: #667eea;
    color: white;
    width: 100%;
}

.btn-primary:hover {
    background: #5a6fd8;
    transform: translateY(-2px);
}

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

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

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

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

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

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

.default-credentials {
    margin-top: 1rem;
    padding: 1rem;
    background: #f8f9fa;
    border-radius: 5px;
    text-align: center;
    font-size: 0.9rem;
}

/* Main App */
.header {
    background: white;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    padding: 1rem 0;
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 1rem;
}

.header h1 {
    color: #333;
    font-size: 1.8rem;
}

.user-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.navbar {
    background: #2c3e50;
    padding: 0;
}

.nav-content {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    padding: 0 1rem;
}

.nav-btn {
    background: none;
    border: none;
    color: white;
    padding: 1rem 1.5rem;
    cursor: pointer;
    transition: background 0.3s;
    font-size: 1rem;
}

.nav-btn:hover,
.nav-btn.active {
    background: #34495e;
}

.main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.tab-content {
    display: none;
}

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

/* Dashboard */
.dashboard-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: white;
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    text-align: center;
}

.stat-card h3 {
    color: #666;
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
}

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

.quick-actions {
    background: white;
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    margin-bottom: 2rem;
}

.quick-actions h3 {
    margin-bottom: 1rem;
    color: #333;
}

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

.action-buttons .btn {
    width: auto;
}

.recent-transactions {
    background: white;
    padding: 1.5rem;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

/* Tables */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.section-header h2 {
    color: #333;
}

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

.search-bar input {
    width: 100%;
    max-width: 300px;
    padding: 0.75rem;
    border: 2px solid #ddd;
    border-radius: 5px;
}

.table-container {
    background: white;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    overflow: hidden;
}

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

th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid #eee;
}

th {
    background: #f8f9fa;
    font-weight: 600;
    color: #555;
}

tr:hover {
    background: #f8f9fa;
}

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

.modal-content {
    background: white;
    margin: 5% auto;
    padding: 2rem;
    border-radius: 10px;
    width: 90%;
    max-width: 500px;
    position: relative;
}

.close {
    position: absolute;
    right: 1rem;
    top: 1rem;
    font-size: 1.5rem;
    cursor: pointer;
    color: #999;
}

.close:hover {
    color: #333;
}

/* Responsive */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-content {
        flex-wrap: wrap;
    }
    
    .dashboard-stats {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .section-header {
        flex-direction: column;
        gap: 1rem;
        align-items: flex-start;
    }
}

.low-stock {
    color: #dc3545;
    font-weight: bold;
}

.high-stock {
    color: #28a745;
}