:root {
    --primary: 210 100% 45%; /* #0066E6 */
    --primary-hover: 210 100% 40%; /* #0052CC */
    --secondary: 210 15% 85%; /* #D4D9E0 */
    --success: 140 65% 45%; /* #28A745 */
    --success-hover: 140 65% 40%; /* #218838 */
    --background: 210 11% 98%; /* #F5F7FA */
    --surface: 0 0% 100%; /* #FFFFFF */
    --text-primary: 220 25% 15%; /* #1F2937 */
    --text-secondary: 220 15% 45%; /* #6B7280 */
    --border: 210 15% 90%; /* #E5E7EB */
    --border-hover: 210 15% 80%; /* #D1D5DB */
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.15);
    --radius: 8px;
    --radius-lg: 12px;
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: hsl(var(--text-primary));
    background: hsl(var(--background));
    font-size: 16px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--spacing-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background: hsl(var(--surface));
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-xl);
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.logo-section {
    flex-shrink: 0;
}

.logo-upload {
    position: relative;
    cursor: pointer;
}

.logo-placeholder {
    width: 120px;
    height: 80px;
    border: 2px dashed hsl(var(--border));
    border-radius: var(--radius);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
    background: hsl(var(--background));
}

.logo-placeholder:hover {
    border-color: hsl(var(--primary));
    background: hsl(var(--primary) / 0.05);
}

.logo-placeholder i {
    font-size: 1.5rem;
    color: hsl(var(--text-secondary));
    margin-bottom: var(--spacing-xs);
}

.logo-placeholder span {
    font-weight: 500;
    color: hsl(var(--text-secondary));
    font-size: 0.9rem;
}

.logo-placeholder small {
    font-size: 0.75rem;
    color: hsl(var(--text-secondary));
    margin-top: var(--spacing-xs);
}

.logo-preview {
    max-width: 120px;
    max-height: 80px;
    object-fit: contain;
    border-radius: var(--radius);
}

.header-info h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: hsl(var(--primary));
    margin-bottom: var(--spacing-xs);
}

.tagline {
    color: hsl(var(--text-secondary));
    font-size: 1.1rem;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xl);
}

/* Sections */
section {
    background: hsl(var(--surface));
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow);
}

.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--spacing-lg);
    padding-bottom: var(--spacing-md);
    border-bottom: 1px solid hsl(var(--border));
}

.section-header h2 {
    font-size: 1.25rem;
    font-weight: 600;
    color: hsl(var(--text-primary));
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.section-header i {
    color: hsl(var(--primary));
}

/* Form Elements */
.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.form-row:last-child {
    margin-bottom: 0;
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group label {
    font-weight: 500;
    color: hsl(var(--text-primary));
    margin-bottom: var(--spacing-sm);
    font-size: 0.9rem;
}

.form-group input,
.form-group select,
.form-group textarea {
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid hsl(var(--border));
    border-radius: var(--radius);
    font-size: 1rem;
    transition: all 0.3s ease;
    background: hsl(var(--surface));
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: hsl(var(--primary));
    box-shadow: 0 0 0 3px hsl(var(--primary) / 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 80px;
}

.input-group {
    display: flex;
    gap: var(--spacing-sm);
}

.input-group input {
    flex: 1;
}

/* Buttons */
.btn-primary,
.btn-secondary,
.btn-success {
    padding: var(--spacing-sm) var(--spacing-lg);
    border: none;
    border-radius: var(--radius);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
}

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

.btn-primary:hover {
    background: hsl(var(--primary-hover));
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.btn-secondary {
    background: hsl(var(--secondary));
    color: hsl(var(--text-primary));
    border: 1px solid hsl(var(--border));
}

.btn-secondary:hover {
    background: hsl(var(--border-hover));
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

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

.btn-success:hover {
    background: hsl(var(--success-hover));
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

/* From/To Container */
.from-to-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
}

/* Items Table */
.table-container {
    overflow-x: auto;
    border-radius: var(--radius);
    border: 1px solid hsl(var(--border));
}

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

.items-table th,
.items-table td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid hsl(var(--border));
}

.items-table th {
    background: hsl(var(--background));
    font-weight: 600;
    color: hsl(var(--text-primary));
}

.items-table td input {
    width: 100%;
    border: none;
    background: transparent;
    padding: var(--spacing-sm);
    font-size: 0.9rem;
}

.items-table td input:focus {
    background: hsl(var(--background));
    border-radius: var(--radius);
}

.items-table .total-cell {
    font-weight: 600;
    color: hsl(var(--primary));
}

.remove-item {
    background: #dc3545;
    color: white;
    border: none;
    border-radius: var(--radius);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    font-size: 0.8rem;
}

.remove-item:hover {
    background: #c82333;
}

/* Payment Method */
.payment-options {
    display: flex;
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.radio-option {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    cursor: pointer;
    font-weight: 500;
}

.radio-option input[type="radio"] {
    display: none;
}

.radio-custom {
    width: 20px;
    height: 20px;
    border: 2px solid hsl(var(--border));
    border-radius: 50%;
    position: relative;
    transition: all 0.3s ease;
}

.radio-option input[type="radio"]:checked + .radio-custom {
    border-color: hsl(var(--primary));
}

.radio-option input[type="radio"]:checked + .radio-custom::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 10px;
    height: 10px;
    background: hsl(var(--primary));
    border-radius: 50%;
}

.payment-details {
    margin-top: var(--spacing-lg);
}

/* Summary */
.summary-container {
    max-width: 400px;
    margin-left: auto;
}

.summary-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-md);
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid hsl(var(--border));
}

.summary-row:last-child {
    border-bottom: none;
}

.summary-row.total {
    font-size: 1.25rem;
    font-weight: 700;
    color: hsl(var(--primary));
    border-top: 2px solid hsl(var(--border));
    padding-top: var(--spacing-md);
}

.summary-row input {
    width: 80px;
    text-align: right;
    border: 1px solid hsl(var(--border));
    border-radius: var(--radius);
    padding: var(--spacing-xs) var(--spacing-sm);
}

/* Actions */
.actions-section {
    text-align: center;
}

.action-buttons {
    display: flex;
    gap: var(--spacing-lg);
    justify-content: center;
    flex-wrap: wrap;
}

/* Footer */
.footer {
    margin-top: var(--spacing-2xl);
    padding: var(--spacing-xl);
    background: hsl(var(--surface));
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.footer-links {
    display: flex;
    gap: var(--spacing-lg);
}

.footer-links a {
    color: hsl(var(--text-secondary));
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer-links a:hover {
    color: hsl(var(--primary));
}

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

.modal-content {
    background: hsl(var(--surface));
    margin: var(--spacing-lg) auto;
    max-width: 90%;
    width: 800px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

.modal-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid hsl(var(--border));
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-actions {
    display: flex;
    gap: var(--spacing-md);
}

.modal-body {
    padding: var(--spacing-lg);
}

/* Invoice Preview */
.invoice-preview {
    background: white;
    padding: var(--spacing-2xl);
    border-radius: var(--radius);
    border: 1px solid hsl(var(--border));
}

.invoice-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-2xl);
}

.invoice-logo img {
    max-width: 150px;
    max-height: 100px;
    object-fit: contain;
}

.invoice-title {
    text-align: right;
}

.invoice-title h1 {
    font-size: 2.5rem;
    color: hsl(var(--primary));
    margin-bottom: var(--spacing-sm);
}

.invoice-parties {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    margin-bottom: var(--spacing-2xl);
}

.party-info h3 {
    font-size: 1.1rem;
    color: hsl(var(--primary));
    margin-bottom: var(--spacing-md);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.invoice-details-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.detail-item {
    padding: var(--spacing-md);
    background: hsl(var(--background));
    border-radius: var(--radius);
}

.detail-label {
    font-size: 0.85rem;
    color: hsl(var(--text-secondary));
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-xs);
}

.detail-value {
    font-weight: 600;
    color: hsl(var(--text-primary));
}

.invoice-items-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: var(--spacing-2xl);
}

.invoice-items-table th,
.invoice-items-table td {
    padding: var(--spacing-md);
    text-align: left;
    border-bottom: 1px solid hsl(var(--border));
}

.invoice-items-table th {
    background: hsl(var(--primary));
    color: white;
    font-weight: 600;
}

.invoice-items-table .text-right {
    text-align: right;
}

.invoice-summary {
    max-width: 400px;
    margin-left: auto;
    margin-bottom: var(--spacing-2xl);
}

.invoice-summary-row {
    display: flex;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid hsl(var(--border));
}

.invoice-summary-row.total {
    font-size: 1.25rem;
    font-weight: 700;
    color: hsl(var(--primary));
    border-top: 2px solid hsl(var(--border));
    padding-top: var(--spacing-md);
}

.invoice-payment {
    background: hsl(var(--background));
    padding: var(--spacing-lg);
    border-radius: var(--radius);
    margin-bottom: var(--spacing-lg);
}

.invoice-payment h3 {
    color: hsl(var(--primary));
    margin-bottom: var(--spacing-md);
}

.invoice-notes {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-xl);
}

.notes-section h3 {
    color: hsl(var(--primary));
    margin-bottom: var(--spacing-md);
    font-size: 1rem;
}

/* Print Styles */
@media print {
    body {
        background: white;
    }
    
    .container {
        padding: 0;
        max-width: none;
    }
    
    .header,
    .footer,
    .actions-section,
    .modal-header {
        display: none;
    }
    
    .main-content {
        display: none;
    }
    
    .modal {
        display: block !important;
        position: static;
        background: none;
    }
    
    .modal-content {
        margin: 0;
        max-width: none;
        width: 100%;
        box-shadow: none;
        border-radius: 0;
    }
    
    .modal-body {
        padding: 0;
    }
    
    .invoice-preview {
        border: none;
        padding: 0;
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-sm);
    }
    
    .header {
        flex-direction: column;
        text-align: center;
        gap: var(--spacing-lg);
    }
    
    .header-info h1 {
        font-size: 2rem;
    }
    
    .from-to-container {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .payment-options {
        flex-direction: column;
        gap: var(--spacing-md);
    }
    
    .action-buttons {
        flex-direction: column;
        align-items: center;
    }
    
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .modal-content {
        max-width: 95%;
        margin: var(--spacing-sm) auto;
    }
    
    .invoice-header {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .invoice-title {
        text-align: center;
    }
    
    .invoice-parties {
        grid-template-columns: 1fr;
    }
    
    .invoice-notes {
        grid-template-columns: 1fr;
    }
    
    .summary-container {
        max-width: 100%;
    }
    
    .invoice-summary {
        max-width: 100%;
    }
}

@media (max-width: 480px) {
    .table-container {
        font-size: 0.8rem;
    }
    
    .items-table th,
    .items-table td {
        padding: var(--spacing-sm);
    }
    
    .invoice-details-grid {
        grid-template-columns: 1fr;
    }
}

/* Navigation Bar */
.navbar {
    background: hsl(var(--surface));
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    margin-bottom: var(--spacing-lg);
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    text-decoration: none;
    color: hsl(var(--text-primary));
}

.nav-logo-img {
    width: 40px;
    height: 40px;
    object-fit: contain;
    border-radius: var(--radius);
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: hsl(var(--primary));
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--spacing-xl);
}

.nav-link {
    color: hsl(var(--text-secondary));
    text-decoration: none;
    font-weight: 500;
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius);
    transition: all 0.3s ease;
}

.nav-link:hover,
.nav-link.active {
    color: hsl(var(--primary));
    background: hsl(var(--primary) / 0.1);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    cursor: pointer;
    gap: 4px;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: hsl(var(--text-primary));
    border-radius: 2px;
    transition: all 0.3s ease;
}

/* Mobile Navigation */
@media (max-width: 768px) {
    .nav-menu {
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        background: hsl(var(--surface));
        flex-direction: column;
        gap: 0;
        padding: var(--spacing-lg) 0;
        box-shadow: var(--shadow);
        transform: translateX(-100%);
        transition: transform 0.3s ease;
    }

    .nav-menu.active {
        transform: translateX(0);
    }

    .nav-link {
        width: 100%;
        text-align: center;
        padding: var(--spacing-md) var(--spacing-lg);
        border-radius: 0;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(7px, -6px);
    }
}

/* Payment Options Grid */
.payment-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus indicators */
button:focus,
input:focus,
select:focus,
textarea:focus {
    outline: 2px solid hsl(var(--primary));
    outline-offset: 2px;
}