:root {
    --primary-color: #4a6bff;
    --primary-hover: #3a56d4;
    --secondary-color: #f0f2f5;
    --secondary-hover: #e0e5eb;
    --text-color: #333;
    --light-text: #666;
    --border-color: #ddd;
    --success-color: #28a745;
    --danger-color: #dc3545;
    --warning-color: #ffc107;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Roboto', sans-serif;
}

body {
    background-color: #f8f9fa;
    color: var(--text-color);
    line-height: 1.6;
}

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

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    flex-wrap: wrap;
    gap: 20px;
}

.logo-container {
    display: flex;
    align-items: center;
    gap: 15px;
}

#logo-preview {
    max-height: 50px;
    max-width: 150px;
    object-fit: contain;
}

h1 {
    font-size: 28px;
    font-weight: 700;
    color: var(--primary-color);
    flex-grow: 1;
    text-align: center;
}

.header-actions {
    display: flex;
    gap: 10px;
}

.tabs {
    display: flex;
    border-bottom: 1px solid var(--border-color);
    margin-bottom: 20px;
}

.tab-btn {
    padding: 12px 20px;
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    font-size: 16px;
    font-weight: 500;
    color: var(--light-text);
    cursor: pointer;
    transition: all 0.3s ease;
}

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

.tab-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

.tab-content {
    display: none;
    padding: 20px 0;
}

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

.form-section {
    background: white;
    border-radius: 8px;
    padding: 25px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

.form-section h2 {
    font-size: 20px;
    margin-bottom: 20px;
    color: var(--primary-color);
}

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

.form-row {
    display: flex;
    gap: 15px;
}

.form-row .form-group {
    flex: 1;
}

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

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="number"],
input[type="date"],
input[type="url"],
textarea,
select {
    width: 100%;
    padding: 10px 15px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 16px;
    transition: border 0.3s ease;
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(74, 107, 255, 0.2);
}

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

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.btn i {
    font-size: 14px;
}

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

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

.btn.secondary {
    background-color: var(--secondary-color);
    color: var(--text-color);
}

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

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

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

/* Items Table */
.items-container {
    background: white;
    border-radius: 8px;
    padding: 25px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
}

#items-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 20px;
}

#items-table th {
    text-align: left;
    padding: 12px 15px;
    background-color: #f8f9fa;
    border-bottom: 2px solid var(--border-color);
    font-weight: 500;
}

#items-table td {
    padding: 10px 15px;
    border-bottom: 1px solid var(--border-color);
    vertical-align: middle;
}

#items-table input {
    width: 100%;
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    border-radius: 4px;
}

#items-table select {
    padding: 8px 12px;
}

.remove-item-btn {
    background: none;
    border: none;
    color: var(--danger-color);
    cursor: pointer;
    font-size: 16px;
    padding: 5px;
}

.remove-item-btn:hover {
    color: #c82333;
}

.totals-section {
    background: white;
    border-radius: 8px;
    padding: 25px;
    box-shadow: var(--shadow);
    margin-left: auto;
    max-width: 300px;
}

.totals-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
    font-size: 16px;
}

.grand-total {
    font-weight: 700;
    font-size: 18px;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

/* Payment Methods */
.payment-methods {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.payment-method {
    display: flex;
    flex-direction: column;
}

.payment-method label {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 15px;
    background-color: var(--secondary-color);
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.payment-method label:hover {
    background-color: var(--secondary-hover);
}

.payment-method label i {
    font-size: 20px;
    color: var(--primary-color);
}

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

.payment-method input[type="radio"]:checked + label {
    background-color: rgba(74, 107, 255, 0.1);
    border-left: 4px solid var(--primary-color);
}

.payment-details {
    padding: 20px;
    background-color: #f8f9fa;
    border-radius: 0 0 4px 4px;
    margin-top: -5px;
    display: none;
}

.payment-method input[type="radio"]:checked ~ .payment-details {
    display: block;
}

/* Preview Tab */
.preview-actions {
    display: flex;
    gap: 15px;
    margin-bottom: 20px;
    justify-content: flex-end;
}

.invoice-preview {
    background: white;
    padding: 40px;
    border-radius: 8px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
}

.invoice-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 30px;
}

#preview-logo {
    max-height: 70px;
    max-width: 200px;
}

.invoice-title h2 {
    font-size: 28px;
    color: var(--primary-color);
    margin-bottom: 10px;
}

.invoice-meta {
    display: flex;
    flex-direction: column;
    gap: 5px;
    font-size: 14px;
}

.invoice-meta div {
    display: flex;
    gap: 10px;
}

.invoice-meta span:first-child {
    font-weight: 500;
    min-width: 80px;
}

.invoice-parties {
    display: flex;
    justify-content: space-between;
    margin-bottom: 30px;
}

.from, .to {
    flex: 0 0 48%;
}

.from h3, .to h3 {
    font-size: 18px;
    margin-bottom: 10px;
    color: var(--primary-color);
}

.invoice-items {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 30px;
}

.invoice-items th {
    text-align: left;
    padding: 12px 15px;
    background-color: #f8f9fa;
    border-bottom: 2px solid var(--border-color);
    font-weight: 500;
}

.invoice-items td {
    padding: 12px 15px;
    border-bottom: 1px solid var(--border-color);
}

.invoice-items tr:last-child td {
    border-bottom: none;
}

.invoice-totals {
    display: flex;
    justify-content: space-between;
    margin-top: 30px;
}

.notes {
    flex: 0 0 60%;
}

.notes h4 {
    margin-bottom: 10px;
    color: var(--primary-color);
}

.totals {
    flex: 0 0 35%;
}

.total-row {
    display: flex;
    justify-content: space-between;
    margin-bottom: 10px;
}

.grand-total {
    font-weight: 700;
    font-size: 18px;
    margin-top: 15px;
    padding-top: 15px;
    border-top: 1px solid var(--border-color);
}

.invoice-payment {
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid var(--border-color);
}

.invoice-payment h3 {
    margin-bottom: 15px;
    color: var(--primary-color);
}

.invoice-payment h4 {
    margin: 15px 0 10px;
    color: var(--primary-color);
}

.action-buttons {
    display: flex;
    justify-content: space-between;
    margin-top: 20px;
}

/* Responsive Styles */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        align-items: flex-start;
    }

    h1 {
        text-align: left;
        margin: 10px 0;
    }

    .form-row {
        flex-direction: column;
        gap: 0;
    }

    .invoice-parties {
        flex-direction: column;
        gap: 20px;
    }

    .invoice-totals {
        flex-direction: column;
        gap: 20px;
    }

    .preview-actions {
        flex-direction: column;
        align-items: flex-start;
    }

    .invoice-preview {
        padding: 20px;
    }

    .invoice-header {
        flex-direction: column;
        gap: 20px;
    }
}

@media (max-width: 480px) {
    .tabs {
        overflow-x: auto;
        white-space: nowrap;
        padding-bottom: 5px;
    }

    .tab-btn {
        padding: 10px 15px;
    }

    #items-table {
        display: block;
        overflow-x: auto;
    }
}