:root {
    /* Light Theme Colors */
    --light-bg-primary: #F8F9FA;
    --light-bg-secondary: #FFFFFF;
    --light-text-primary: #1A1A1A;
    --light-text-secondary: #555555;
    --light-input-bg: #FFFFFF;
    --light-input-border: #CCCCCC;
    --light-border: #DDDDDD;
    --light-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    --light-hover: #F0F0F0;

    /* Dark Theme Colors */
    --dark-bg-primary: #0F0F0F;
    --dark-bg-secondary: #1A1A1A;
    --dark-text-primary: #E8E8E8;
    --dark-text-secondary: #B0B0B0;
    --dark-input-bg: #2A2A2A;
    --dark-input-border: #444444;
    --dark-border: #333333;
    --dark-shadow: 0 2px 8px rgba(0, 0, 0, 0.5);
    --dark-hover: #2A2A2A;

    /* Default to dark theme */
    --bg-primary: var(--dark-bg-primary);
    --bg-secondary: var(--dark-bg-secondary);
    --text-primary: var(--dark-text-primary);
    --text-secondary: var(--dark-text-secondary);
    --input-bg: var(--dark-input-bg);
    --input-border: var(--dark-input-border);
    --border: var(--dark-border);
    --shadow: var(--dark-shadow);
    --hover: var(--dark-hover);

    /* Accent Colors */
    --accent-color: #0066CC;
    --accent-hover: #0052A3;
}

/* Light Theme */
body.light {
    --bg-primary: var(--light-bg-primary);
    --bg-secondary: var(--light-bg-secondary);
    --text-primary: var(--light-text-primary);
    --text-secondary: var(--light-text-secondary);
    --input-bg: var(--light-input-bg);
    --input-border: var(--light-input-border);
    --border: var(--light-border);
    --shadow: var(--light-shadow);
    --hover: var(--light-hover);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
    max-width: 100%;
    margin: 0 auto;
}

/* Header */
.header {
    background-color: var(--bg-secondary);
    padding: 1.5rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
    transition: background-color 0.3s ease;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.header-actions {
    display: flex;
    gap: 1rem;
    align-items: center;
}

/* Main Content Layout */
.main-content {
    display: grid;
    grid-template-columns: 400px 1fr;
    gap: 2rem;
    padding: 2rem;
    min-height: calc(100vh - 100px);
}

/* Control Panel */
.control-panel {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    max-height: calc(100vh - 140px);
    overflow-y: auto;
    transition: background-color 0.3s ease;
}

.control-panel::-webkit-scrollbar {
    width: 8px;
}

.control-panel::-webkit-scrollbar-track {
    background: var(--bg-primary);
    border-radius: 4px;
}

.control-panel::-webkit-scrollbar-thumb {
    background: var(--input-border);
    border-radius: 4px;
}

.control-panel::-webkit-scrollbar-thumb:hover {
    background: var(--accent-color);
}

/* Sections */
.section {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border);
}

.section:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.section h2 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--text-primary);
    font-weight: 600;
}

/* Form Elements */
.form-group {
    margin-bottom: 1rem;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-secondary);
}

input[type="text"],
input[type="email"],
input[type="tel"],
input[type="date"],
input[type="number"],
select,
textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    background-color: var(--input-bg);
    color: var(--text-primary);
    font-size: 0.95rem;
    transition: border-color 0.3s ease, background-color 0.3s ease;
}

input[type="text"]:focus,
input[type="email"]:focus,
input[type="tel"]:focus,
input[type="date"]:focus,
input[type="number"]:focus,
select:focus,
textarea:focus {
    outline: none;
    border-color: var(--accent-color);
}

input[type="file"] {
    width: 100%;
    padding: 0.5rem;
    border: 1px solid var(--input-border);
    border-radius: 6px;
    background-color: var(--input-bg);
    color: var(--text-primary);
    font-size: 0.9rem;
}

input[type="range"] {
    width: 100%;
    margin-top: 0.5rem;
}

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

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

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

.btn-primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 102, 204, 0.3);
}

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

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

.btn-icon {
    padding: 0.5rem;
    font-size: 1.3rem;
    background-color: var(--input-bg);
    border: 1px solid var(--input-border);
}

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

.btn-block {
    width: 100%;
}

.btn-large {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    font-weight: 600;
}

.btn-danger {
    background-color: #dc3545;
    color: white;
    padding: 0.5rem 1rem;
    font-size: 0.85rem;
}

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

/* Logo Preview */
#logoPreviewContainer {
    margin-top: 1rem;
    padding: 1rem;
    background-color: var(--bg-primary);
    border-radius: 6px;
    border: 1px solid var(--border);
}

#logoPreview {
    width: 100%;
    max-height: 150px;
    object-fit: contain;
    margin-bottom: 1rem;
    border-radius: 4px;
}

/* Line Items */
.line-item {
    background-color: var(--bg-primary);
    padding: 1rem;
    border-radius: 6px;
    margin-bottom: 1rem;
    border: 1px solid var(--border);
}

.line-item-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.75rem;
}

.line-item-header h4 {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

/* Preview Panel */
.preview-panel {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding: 1rem;
}

.invoice-preview {
    width: 100%;
    max-width: 800px;
    background-color: #FFFFFF;
    color: #000000;
    padding: 3rem;
    border-radius: 8px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
    min-height: 1100px;
}

/* Invoice Logo */
.invoice-logo {
    margin-bottom: 2rem;
    text-align: center;
}

.invoice-logo.left {
    text-align: left;
}

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

#invoiceLogoImg {
    max-width: 200px;
    height: auto;
    object-fit: contain;
}

/* Invoice Header */
.invoice-header {
    text-align: center;
    margin-bottom: 2rem;
}

.invoice-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-color);
    letter-spacing: 2px;
}

/* Invoice Meta */
.invoice-meta {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
    margin-bottom: 2rem;
    padding: 1rem;
    background-color: #F8F9FA;
    border-radius: 6px;
}

.invoice-meta div {
    font-size: 0.9rem;
}

.invoice-meta strong {
    color: #555;
}

/* Invoice Parties */
.invoice-parties {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.party h3 {
    font-size: 0.85rem;
    font-weight: 700;
    color: #666;
    text-transform: uppercase;
    letter-spacing: 1px;
    margin-bottom: 0.75rem;
    border-bottom: 2px solid var(--accent-color);
    padding-bottom: 0.5rem;
}

.party strong {
    font-size: 1.1rem;
    color: #000;
}

.party span {
    font-size: 0.9rem;
    color: #555;
}

/* Invoice Table */
.invoice-table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 2rem;
}

.invoice-table thead {
    background-color: var(--accent-color);
    color: white;
}

.invoice-table th {
    padding: 1rem;
    text-align: left;
    font-weight: 600;
    font-size: 0.9rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.invoice-table td {
    padding: 1rem;
    border-bottom: 1px solid #E0E0E0;
    font-size: 0.95rem;
}

.invoice-table tbody tr:hover {
    background-color: #F8F9FA;
}

.text-center {
    text-align: center;
}

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

/* Invoice Totals */
.invoice-totals {
    margin-left: auto;
    width: 300px;
    margin-bottom: 2rem;
}

.total-row {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem 0;
    font-size: 1rem;
    border-bottom: 1px solid #E0E0E0;
}

.total-final {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent-color);
    border-bottom: 3px double var(--accent-color);
    margin-top: 0.5rem;
    padding-top: 1rem;
}

/* Invoice Notes */
.invoice-notes {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 2px solid #E0E0E0;
}

.invoice-notes p {
    font-size: 0.95rem;
    color: #555;
    line-height: 1.8;
}

/* Template Styles */
.invoice-preview.minimal .invoice-header h1 {
    font-weight: 400;
    letter-spacing: 4px;
}

.invoice-preview.minimal .invoice-table thead {
    background-color: #333;
}

.invoice-preview.colorful .invoice-header h1 {
    background: linear-gradient(135deg, var(--accent-color), #00D4FF);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.invoice-preview.colorful .invoice-table thead {
    background: linear-gradient(135deg, var(--accent-color), #0052A3);
}

/* Responsive Design */
@media (max-width: 1200px) {
    .main-content {
        grid-template-columns: 350px 1fr;
    }
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
    }

    .control-panel {
        max-height: none;
    }

    .invoice-preview {
        padding: 2rem;
    }
}

@media (max-width: 768px) {
    .header {
        padding: 1rem;
    }

    .logo {
        font-size: 1.2rem;
    }

    .main-content {
        padding: 1rem;
        gap: 1rem;
    }

    .control-panel {
        padding: 1.5rem;
    }

    .invoice-preview {
        padding: 1.5rem;
        min-height: auto;
    }

    .invoice-header h1 {
        font-size: 2rem;
    }

    .invoice-parties {
        grid-template-columns: 1fr;
        gap: 1.5rem;
    }

    .invoice-meta {
        grid-template-columns: 1fr;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .invoice-totals {
        width: 100%;
    }
}

@media (max-width: 480px) {
    .invoice-preview {
        padding: 1rem;
    }

    .invoice-header h1 {
        font-size: 1.5rem;
    }

    .invoice-table {
        font-size: 0.85rem;
    }

    .invoice-table th,
    .invoice-table td {
        padding: 0.5rem;
    }
}