:root {
    --primary-color: #4a6fa5;
    --primary-hover: #5c82bb;
    --secondary-color: #dbe9ff;
    --accent-color: #ff6b6b;
    --text-color: #333;
    --light-text: #666;
    --border-color: #ddd;
    --success-color: #28a745;
    --success-light: #d4edda;
    --danger-color: #dc3545;
    --danger-light: #f8d7da;
    --shadow: 0 2px 5px rgba(0,0,0,0.1);
    --card-border-radius: 8px;
    --background-color: #F5F5F5;
    --card-bg: #FFFFFF;
    --light-gray: #f5f5f5;
    --modal-overlay: rgba(0, 0, 0, 0.5);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: #f9f9f9;
    color: var(--text-color);
    line-height: 1.6;
    min-height: 100vh;
    padding-bottom: 20px;
}

.app-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 15px;
    position: relative;
}

header {
    background-color: var(--primary-color);
    color: white;
    padding: 15px 20px;
    margin-bottom: 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
    position: relative;
}

header h1 {
    font-size: 1.5rem;
    margin: 0;
    white-space: nowrap;
}

.container {
    background-color: white;
    padding: 20px;
    border-radius: var(--card-border-radius);
    box-shadow: var(--shadow);
    margin-bottom: 20px;
    overflow: hidden;
}

.action-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.btn {
    background-color: #f0f0f0;
    color: var(--text-color);
    border: none;
    padding: 8px 15px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    display: inline-flex;
    align-items: center;
    transition: all 0.2s;
    box-shadow: var(--shadow);
}

.btn:hover {
    background-color: #e0e0e0;
}

.btn i {
    margin-right: 5px;
}

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

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

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

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

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

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

.action-buttons {
    display: flex;
    gap: 10px;
    margin: 15px 0;
}

.search-box {
    margin-bottom: 15px;
}

.search-box input {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
}

.list-container {
    max-height: 70vh;
    overflow-y: auto;
    margin-bottom: 20px;
}

.customer-card {
    background-color: white;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--primary-color);
    border-radius: var(--card-border-radius);
    padding: 15px;
    margin-bottom: 10px;
    display: flex;
    justify-content: space-between;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: transform 0.2s;
}

.customer-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.customer-card.no-debt {
    border-left: 4px solid var(--success-color);
}

.customer-info {
    flex: 1;
    overflow: hidden;
    padding-right: 10px;
}

.customer-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}

.customer-name {
    font-weight: 600;
    font-size: 1.1rem;
    margin-bottom: 5px;
}

.customer-debt {
    color: var(--danger-color);
    font-weight: 600;
}

.customer-debt.paid {
    color: var(--success-color);
}

.debt-card {
    background-color: white;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--danger-color);
    border-radius: var(--card-border-radius);
    padding: 12px;
    margin-bottom: 10px;
}

.debt-card-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 8px;
}

.debt-amount {
    color: var(--danger-color);
    font-weight: 600;
}

.debt-date {
    color: var(--light-text);
    font-size: 0.85rem;
    margin-top: 8px;
}

.payment-card {
    background-color: white;
    border: 1px solid var(--border-color);
    border-left: 4px solid var(--success-color);
    border-radius: var(--card-border-radius);
    padding: 12px;
    margin-bottom: 10px;
}

.payment-amount {
    color: var(--success-color);
    font-weight: 600;
}

.total-debt {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--danger-color);
    background-color: var(--danger-light);
    padding: 10px;
    border-radius: 4px;
    margin-bottom: 15px;
}

/* Modal styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    overflow-y: auto;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.modal.active {
    display: flex;
    opacity: 1;
}

.modal:not(.hidden) {
    animation: fadeIn 0.3s ease forwards;
}

.modal-content {
    background-color: white;
    padding: 25px;
    border-radius: 8px;
    max-width: 500px;
    width: 90%;
    position: relative;
    box-shadow: 0 4px 20px rgba(0,0,0,0.2);
    transform: translateY(-20px);
    transition: transform 0.3s ease;
}

.modal.active .modal-content {
    transform: translateY(0);
}

.close {
    position: absolute;
    right: 15px;
    top: 15px;
    font-size: 24px;
    cursor: pointer;
    color: #aaa;
    transition: color 0.2s;
}

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

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

.form-group label {
    display: block;
    margin-bottom: 5px;
    font-weight: 500;
    color: var(--text-color);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 1rem;
}

.form-group textarea {
    width: 100%;
    height: 100px;
    padding: 10px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

.form-actions {
    display: flex;
    justify-content: flex-end;
    gap: 10px;
    margin-top: 20px;
}

.cancel-btn {
    background-color: #f0f0f0;
}

.cancel-btn:hover {
    background-color: #e0e0e0;
}

.hidden {
    display: none !important;
}

/* Status indicator for Excel */
.status-indicator {
    position: absolute;
    right: 10px;
    top: 50px;
    font-size: 0.8rem;
    background-color: rgba(255, 255, 255, 0.2);
    padding: 3px 8px;
    border-radius: 4px;
}

.status-indicator .connected {
    color: #aaff99;
}

.status-indicator .disconnected {
    color: #ffaa99;
}

.status-indicator .remote-access {
    color: #ffee99;
}

.read-only-notice {
    background-color: #fff3cd;
    border: 1px solid #ffeeba;
    color: #856404;
    padding: 8px 12px;
    margin-bottom: 15px;
    border-radius: 4px;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Tab navigation */
.tab-navigation {
    display: flex;
    margin-bottom: 20px;
    border-bottom: 1px solid var(--border-color);
    overflow-x: auto;
    scrollbar-width: none; /* Firefox */
}

.tab-navigation::-webkit-scrollbar {
    display: none; /* Chrome, Safari, Edge */
}

.tab-button {
    padding: 12px 18px;
    background-color: transparent;
    border: none;
    border-bottom: 3px solid transparent;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: var(--light-text);
    transition: all 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
}

.tab-button:hover {
    color: var(--primary-color);
}

.tab-button.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
    background-color: rgba(74, 111, 165, 0.1);
}

.tab-content {
    display: none;
    opacity: 0;
    transition: opacity 0.3s;
    padding: 10px 0;
}

.tab-content.active {
    display: block;
    opacity: 1;
}

/* Customer detail header */
.detail-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    flex-wrap: wrap;
    gap: 10px;
}

#selected-customer-name {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--text-color);
}

#selected-customer-total {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--danger-color);
    padding: 6px 12px;
    border-radius: 4px;
}

#selected-customer-total.paid {
    color: var(--success-color);
}

.orphaned-transaction {
    opacity: 0.7;
    position: relative;
}

.orphaned-transaction::after {
    content: "⚠️ Khách hàng đã bị xóa";
    position: absolute;
    top: 5px;
    right: 5px;
    font-size: 0.7rem;
    color: #ff7b00;
}

.transaction-customer {
    font-weight: 600;
    margin-bottom: 5px;
    font-size: 1rem;
}

.transaction-card {
    padding: 15px;
    border-radius: var(--card-border-radius);
    margin-bottom: 10px;
    cursor: pointer;
}

.transaction-card:hover {
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.payment-amount {
    color: var(--success-color);
    font-weight: 600;
}

.transaction-actions {
    display: flex;
    justify-content: flex-end;
    gap: 8px;
    margin-top: 8px;
}

.btn-edit, .btn-delete {
    background-color: transparent;
    border: none;
    cursor: pointer;
    font-size: 0.9rem;
    width: 30px;
    height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--light-text);
}

.btn-edit {
    background-color: rgba(0, 123, 255, 0.1);
}

.btn-delete {
    background-color: rgba(220, 53, 69, 0.1);
}

.btn-edit:hover {
    background-color: rgba(0, 123, 255, 0.2);
}

.btn-delete:hover {
    background-color: rgba(220, 53, 69, 0.2);
}

.btn-edit-customer, .btn-delete-customer {
    background-color: transparent;
    border: none;
    cursor: pointer;
    font-size: 1rem;
    width: 35px;
    height: 35px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background-color 0.2s;
}

.btn-edit-customer {
    color: var(--primary-color);
}

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

.btn-edit-customer:hover {
    background-color: rgba(0, 123, 255, 0.1);
    color: #0056b3;
}

.btn-delete-customer:hover {
    background-color: rgba(220, 53, 69, 0.1);
    color: #b21f2d;
}

/* Pagination */
.pagination {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 10px;
    margin-top: 20px;
    flex-wrap: wrap;
}

.pagination-btn {
    padding: 5px 12px;
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.2s;
}

.pagination-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

.pagination-info {
    font-size: 0.9rem;
    color: var(--light-text);
    padding: 5px 10px;
}

/* Header Actions & Hamburger Menu */
.header-actions {
    display: flex;
    gap: 10px;
    align-items: center;
}

/* Hamburger Menu for Mobile */
.menu-toggle {
    display: none;
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
    position: relative;
    z-index: 1001;
    padding: 12px;
    margin-right: -8px;
    min-width: 44px;
    min-height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.menu-toggle i {
    pointer-events: none; /* This ensures clicks on the icon propagate to the button */
}

/* Back button styling */
#back-to-list-btn {
    background-color: rgba(255, 255, 255, 0.2);
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
    font-weight: bold;
    transition: all 0.3s;
    padding: 10px 15px;
}

#back-to-list-btn:hover {
    background-color: var(--primary-color);
    color: white;
}

#back-to-list-btn i {
    margin-right: 8px;
}

/* Help Content */
.help-content {
    max-width: 800px;
    max-height: 80vh;
    overflow-y: auto;
    padding-right: 20px;
}

.help-section {
    margin-bottom: 25px;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 20px;
}

.help-section:last-child {
    border-bottom: none;
}

.help-section h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: 1.2rem;
}

.help-section p {
    margin-bottom: 10px;
}

.help-section ol, 
.help-section ul {
    margin-left: 20px;
    margin-bottom: 15px;
}

.help-section li {
    margin-bottom: 8px;
}

.help-section strong {
    color: var(--primary-color);
    font-weight: 600;
}

/* Login page styles */
.login-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    background-color: #f5f8ff;
}

.login-box {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    padding: 30px;
    width: 90%;
    max-width: 400px;
}

.login-box h2 {
    text-align: center;
    margin-bottom: 20px;
    color: var(--primary-color);
}

.login-icon {
    text-align: center;
    margin-bottom: 25px;
    color: var(--primary-color);
}

.login-help {
    background-color: #e9f5ff;
    border: 1px solid #c7e5ff;
    border-radius: 4px;
    padding: 15px;
    margin-top: 30px;
    font-size: 0.9rem;
    color: #0056b3;
}

.login-help code {
    background-color: rgba(0,0,0,0.05);
    padding: 2px 5px;
    border-radius: 3px;
    font-family: monospace;
    font-size: 0.95em;
}

.login-note {
    text-align: center;
    margin-top: 20px;
    color: var(--light-text);
    font-size: 0.85rem;
    font-style: italic;
}

.excel-setup {
    margin-top: 20px;
    padding: 15px;
    background-color: #e8f5e9;
    border-radius: 4px;
    font-size: 0.9rem;
}

.excel-setup p {
    margin-bottom: 15px;
    color: #2e7d32;
}

.excel-btn {
    background-color: #2e7d32;
    color: white;
    text-decoration: none;
    display: inline-block;
    width: 100%;
    text-align: center;
}

.excel-btn:hover {
    background-color: #1b5e20;
    color: white;
}

.login-instruction {
    background-color: #f8f9fa;
    border-left: 4px solid #ddd;
    padding: 15px;
    margin: 20px 0;
    font-size: 0.95rem;
    color: #495057;
}

.login-instruction i {
    margin-right: 5px;
    color: var(--primary-color);
}

.error-message {
    color: var(--danger-color);
    background-color: var(--danger-light);
    padding: 10px;
    border-radius: 4px;
    margin-bottom: 15px;
}

.no-data {
    text-align: center;
    color: var(--light-text);
    padding: 30px 0;
    font-style: italic;
}

/* Media queries for responsiveness */
@media (max-width: 768px) {
    /* Mobile header */
    header {
        padding: 12px 15px;
    }
    
    header h1 {
        font-size: 1.3rem;
    }
    
    /* Mobile hamburger menu */
    .menu-toggle {
        display: flex;
        position: relative;
        z-index: 1001;
        padding: 12px;
        margin-right: -8px;
    }
    
    .header-actions {
        position: absolute;
        top: 100%;
        right: 0;
        flex-direction: column;
        background-color: var(--primary-color);
        width: 200px;
        padding: 15px;
        border-top: 1px solid rgba(255,255,255,0.1);
        box-shadow: 0 5px 10px rgba(0,0,0,0.2);
        z-index: 1000;
        transform: translateY(-200%);
        transition: transform 0.3s ease;
        opacity: 0;
    }
    
    .header-actions.active {
        transform: translateY(0);
        opacity: 1;
    }
    
    .header-actions .btn {
        width: 100%;
        margin-bottom: 8px;
        justify-content: flex-start;
    }
    
    /* Improve section header layout */
    .section-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }
    
    .section-header button {
        width: 100%;
        justify-content: center;
    }
    
    /* Improve tab button visibility */
    .tab-button {
        flex: 1;
        justify-content: center;
        padding: 12px 5px;
        font-size: 0.9rem;
    }
    
    .tab-button.active {
        background-color: rgba(74, 111, 165, 0.2);
        border-bottom-width: 3px;
        color: var(--primary-color);
        font-weight: bold;
    }
    
    .tab-button i {
        margin-right: 5px;
    }
    
    /* Improve back button visibility */
    #back-to-list-btn {
        background-color: var(--primary-color);
        color: white;
        padding: 10px 15px;
        width: 100%;
        border-radius: 4px;
        display: flex;
        align-items: center;
        justify-content: center;
        font-weight: 600;
        box-shadow: 0 2px 5px rgba(0,0,0,0.2);
        margin-bottom: 10px;
    }
    
    /* Container padding */
    .container {
        padding: 15px 10px;
    }
    
    .modal-content {
        padding: 20px 15px;
        width: 95%;
    }
    
    /* Customer detail view */
    .detail-header {
        flex-direction: column;
        align-items: flex-start;
        width: 100%;
    }
    
    #selected-customer-name {
        font-size: 1.3rem;
        width: 100%;
        margin-bottom: 5px;
    }
    
    #selected-customer-total {
        font-size: 1.1rem;
        width: 100%;
        text-align: center;
        margin-bottom: 10px;
    }
    
    /* Full width action buttons */
    .action-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .action-buttons .btn {
        width: 100%;
        padding: 10px 12px;
        font-size: 0.9rem;
        justify-content: center;
    }
    
    /* Card styling for mobile */
    .customer-card,
    .debt-card,
    .payment-card,
    .transaction-card {
        padding: 12px 10px;
    }
    
    .customer-debt {
        font-size: 0.95rem;
    }
    
    /* Form elements */
    .form-group input,
    .form-group select,
    .form-group textarea {
        padding: 8px;
        font-size: 0.95rem;
    }
    
    /* Help modal for small screens */
    .help-content {
        max-width: 100%;
        padding-right: 10px;
    }
}

/* Animation keyframes */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* Section header */
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.section-header h2 {
    font-size: 1.3rem;
    margin: 0;
}

/* Mobile menu backdrop */
.menu-backdrop {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.menu-backdrop.active {
    display: block;
    opacity: 1;
}