:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --border-color: #dee2e6;
    --accent-color: #0066cc;
    --accent-hover: #0052a3;
    --accent-light: #e7f3ff;
    --error-color: #dc3545;
    --success-color: #28a745;
    --panel-bg: #ffffff;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.12);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-accent: linear-gradient(135deg, #0066cc 0%, #0052a3 100%);
}

[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3a3a3a;
    --text-primary: #e8e8e8;
    --text-secondary: #aaaaaa;
    --border-color: #444444;
    --accent-color: #4da6ff;
    --accent-hover: #66b3ff;
    --accent-light: #1a3a5c;
    --error-color: #ff6b6b;
    --success-color: #51cf66;
    --panel-bg: #252525;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.5);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.5);
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-accent: linear-gradient(135deg, #4da6ff 0%, #66b3ff 100%);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Helvetica Neue', sans-serif;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
    min-height: 100vh;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

@media (max-width: 768px) {
    .container {
        padding: 15px;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 10px;
    }
}

header {
    margin-bottom: 30px;
    padding: 25px 0;
    border-bottom: 2px solid var(--border-color);
    background: linear-gradient(135deg, rgba(0, 102, 204, 0.05) 0%, rgba(0, 82, 163, 0.05) 100%);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
}

header h1 {
    font-size: 2.8em;
    margin-bottom: 8px;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    letter-spacing: -0.5px;
}

.tagline {
    color: var(--text-secondary);
    font-size: 1.1em;
    margin-bottom: 20px;
}

@media (max-width: 768px) {
    header {
        padding: 20px;
        margin-bottom: 20px;
    }

    header h1 {
        font-size: 2.2em;
    }

    .tagline {
        font-size: 1em;
        margin-bottom: 15px;
    }
}

@media (max-width: 480px) {
    header {
        padding: 15px;
        margin-bottom: 15px;
    }

    header h1 {
        font-size: 1.8em;
    }

    .tagline {
        font-size: 0.9em;
        margin-bottom: 12px;
    }
}

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

@media (max-width: 768px) {
    .header-controls {
        gap: 8px;
    }

    .header-controls button {
        flex: 1 1 calc(50% - 4px);
        min-width: 120px;
    }
}

@media (max-width: 480px) {
    .header-controls {
        flex-direction: column;
        gap: 8px;
    }

    .header-controls button {
        flex: 1;
        width: 100%;
    }
}

.info-section {
    background: linear-gradient(135deg, var(--panel-bg) 0%, var(--bg-secondary) 100%);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 30px;
    margin-bottom: 30px;
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.info-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-accent);
}

.info-content h3 {
    font-size: 1.4em;
    color: var(--accent-color);
    margin-bottom: 20px;
}

.info-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}

.info-item {
    padding: 20px;
    background-color: var(--panel-bg);
    border-radius: 10px;
    border-left: 4px solid var(--accent-color);
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.info-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-hover);
}

.info-item strong {
    display: block;
    color: var(--accent-color);
    font-size: 1.1em;
    margin-bottom: 8px;
}

.info-item p {
    color: var(--text-secondary);
    font-size: 0.95em;
    line-height: 1.5;
    margin: 0;
}

.info-quick-start {
    padding: 15px;
    background-color: var(--bg-secondary);
    border-radius: 6px;
    border: 1px dashed var(--accent-color);
    text-align: center;
    color: var(--text-primary);
    font-size: 1em;
}

.info-quick-start strong {
    color: var(--accent-color);
}

@media (max-width: 1024px) {
    .info-section {
        padding: 25px;
    }

    .info-grid {
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    }
}

@media (max-width: 768px) {
    .info-section {
        padding: 20px;
        margin-bottom: 20px;
    }

    .info-content h3 {
        font-size: 1.2em;
    }

    .info-grid {
        grid-template-columns: 1fr;
        gap: 15px;
    }

    .info-item {
        padding: 15px;
    }

    .info-quick-start {
        padding: 12px;
        font-size: 0.9em;
    }
}

@media (max-width: 480px) {
    .info-section {
        padding: 15px;
        margin-bottom: 15px;
    }

    .info-content h3 {
        font-size: 1.1em;
    }

    .info-item {
        padding: 12px;
    }
}

.btn-primary, .btn-secondary, .btn-small {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow);
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
}

@media (max-width: 768px) {
    .btn-primary, .btn-secondary {
        padding: 14px 20px;
        font-size: 14px;
    }

    .btn-small {
        padding: 10px 14px;
        font-size: 12px;
    }
}

@media (max-width: 480px) {
    .btn-primary, .btn-secondary {
        padding: 12px 16px;
        font-size: 13px;
    }

    .btn-small {
        padding: 8px 12px;
        font-size: 11px;
    }
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    background-color: var(--panel-bg);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    background-color: var(--bg-secondary);
    border-color: var(--accent-color);
    color: var(--accent-color);
    transform: translateY(-1px);
}

.btn-small {
    padding: 8px 16px;
    font-size: 13px;
    background-color: var(--panel-bg);
    color: var(--text-primary);
    border: 2px solid var(--border-color);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.btn-small:hover {
    background-color: var(--accent-light);
    border-color: var(--accent-color);
    color: var(--accent-color);
    transform: translateY(-1px);
    box-shadow: var(--shadow);
}

.main-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
    margin-bottom: 30px;
}

@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}

@media (max-width: 768px) {
    .main-content {
        gap: 15px;
        margin-bottom: 20px;
    }
}

@media (max-width: 480px) {
    .main-content {
        gap: 12px;
        margin-bottom: 15px;
    }
}

.editor-panel, .details-panel, .output-panel {
    background-color: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 25px;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
    position: relative;
}

.editor-panel:hover, .details-panel:hover, .output-panel:hover {
    box-shadow: var(--shadow-hover);
}

@media (max-width: 768px) {
    .editor-panel, .details-panel, .output-panel {
        padding: 20px;
        border-radius: 10px;
    }
}

@media (max-width: 480px) {
    .editor-panel, .details-panel, .output-panel {
        padding: 15px;
        border-radius: 8px;
    }
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 1px solid var(--border-color);
    flex-wrap: wrap;
    gap: 10px;
}

.panel-header h2 {
    font-size: 1.3em;
    color: var(--text-primary);
}

@media (max-width: 768px) {
    .panel-header {
        margin-bottom: 15px;
        padding-bottom: 12px;
    }

    .panel-header h2 {
        font-size: 1.2em;
    }
}

@media (max-width: 480px) {
    .panel-header {
        margin-bottom: 12px;
        padding-bottom: 10px;
    }

    .panel-header h2 {
        font-size: 1.1em;
    }
}

.panel-description {
    margin-bottom: 15px;
    padding: 12px;
    background-color: var(--bg-secondary);
    border-radius: 6px;
    border-left: 3px solid var(--accent-color);
}

.panel-description p {
    margin: 0;
    font-size: 0.9em;
    color: var(--text-secondary);
    line-height: 1.5;
}

.panel-description strong {
    color: var(--accent-color);
    font-weight: 600;
}

@media (max-width: 768px) {
    .panel-description {
        padding: 10px;
        margin-bottom: 12px;
    }

    .panel-description p {
        font-size: 0.85em;
    }
}

@media (max-width: 480px) {
    .panel-description {
        padding: 8px;
        margin-bottom: 10px;
    }

    .panel-description p {
        font-size: 0.8em;
    }
}

.parts-tree {
    min-height: 400px;
}

@media (max-width: 768px) {
    .parts-tree {
        min-height: 300px;
    }
}

@media (max-width: 480px) {
    .parts-tree {
        min-height: 250px;
    }
}

.tree-item {
    margin: 6px 0;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    background-color: var(--panel-bg);
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    touch-action: manipulation;
    -webkit-tap-highlight-color: transparent;
}

@media (max-width: 768px) {
    .tree-item {
        padding: 10px 14px;
        margin: 5px 0;
    }
}

@media (max-width: 480px) {
    .tree-item {
        padding: 8px 12px;
        margin: 4px 0;
        border-radius: 8px;
    }

    .tree-item:hover {
        transform: translateX(2px);
    }

    .tree-item.selected {
        transform: translateX(2px);
    }
}

.tree-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 0;
    background: var(--gradient-accent);
    border-radius: 10px 0 0 10px;
    transition: width 0.3s ease;
}

.tree-item:hover {
    background-color: var(--accent-light);
    border-color: var(--accent-color);
    transform: translateX(5px);
    box-shadow: var(--shadow);
}

.tree-item:hover::before {
    width: 4px;
}

.tree-item.selected {
    border-color: var(--accent-color);
    background: linear-gradient(90deg, var(--accent-light) 0%, var(--panel-bg) 100%);
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.15), var(--shadow);
    transform: translateX(3px);
}

.tree-item.selected::before {
    width: 4px;
}

.tree-item-header {
    display: flex;
    align-items: center;
    gap: 10px;
}

.tree-item-icon {
    font-size: 16px;
    width: 20px;
    text-align: center;
}

.tree-item-name {
    flex: 1;
    font-weight: 500;
}

.tree-item-actions {
    display: flex;
    gap: 5px;
}

.tree-item-actions button {
    padding: 4px 8px;
    font-size: 11px;
    background-color: transparent;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    cursor: pointer;
    color: var(--text-secondary);
}

.tree-item-actions button:hover {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.tree-item-children {
    margin-left: 35px;
    margin-top: 10px;
    border-left: 3px solid var(--border-color);
    padding-left: 20px;
    position: relative;
}

@media (max-width: 768px) {
    .tree-item-children {
        margin-left: 25px;
        padding-left: 15px;
    }
}

@media (max-width: 480px) {
    .tree-item-children {
        margin-left: 20px;
        padding-left: 12px;
        border-left-width: 2px;
    }
}

.tree-item-children::before {
    content: '';
    position: absolute;
    left: -3px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: linear-gradient(180deg, var(--accent-color) 0%, transparent 100%);
    opacity: 0.3;
}

.empty-state {
    text-align: center;
    padding: 60px 20px;
    color: var(--text-secondary);
    font-style: italic;
    position: relative;
}

@media (max-width: 768px) {
    .empty-state {
        padding: 40px 15px;
    }
}

@media (max-width: 480px) {
    .empty-state {
        padding: 30px 10px;
    }

    .empty-state::before {
        font-size: 2em;
    }
}

.empty-state::before {
    content: '📦';
    font-size: 3em;
    display: block;
    margin-bottom: 15px;
    opacity: 0.3;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-10px); }
}

.part-details {
    min-height: 400px;
}

@media (max-width: 768px) {
    .part-details {
        min-height: 300px;
    }
}

@media (max-width: 480px) {
    .part-details {
        min-height: 250px;
    }
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 14px;
    transition: all 0.3s ease;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
}

@media (max-width: 768px) {
    .form-group input,
    .form-group textarea,
    .form-group select {
        padding: 14px 16px;
        font-size: 16px; /* Prevents zoom on iOS */
    }
}

@media (max-width: 480px) {
    .form-group input,
    .form-group textarea,
    .form-group select {
        padding: 12px 14px;
        font-size: 16px;
        border-radius: 6px;
    }
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(0, 102, 204, 0.1), var(--shadow);
    transform: translateY(-1px);
}

.form-group input[type="number"] {
    width: 120px;
}

@media (max-width: 480px) {
    .form-group input[type="number"] {
        width: 100%;
    }
}

.form-group.error input,
.form-group.error textarea,
.form-group.error select {
    border-color: var(--error-color);
}

.error-message {
    color: var(--error-color);
    font-size: 12px;
    margin-top: 4px;
}

.output-panel {
    margin-top: 20px;
}

.output-tabs {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

@media (max-width: 768px) {
    .output-tabs {
        gap: 8px;
    }
}

@media (max-width: 480px) {
    .output-tabs {
        flex-direction: column;
        gap: 6px;
    }

    .output-tabs .tab-btn {
        width: 100%;
    }
}

.tab-btn {
    padding: 10px 20px;
    border: none;
    background-color: var(--bg-secondary);
    color: var(--text-secondary);
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.tab-btn.active {
    background: var(--gradient-accent);
    color: white;
    box-shadow: var(--shadow);
}

.tab-btn:hover:not(.active) {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    transform: translateY(-2px);
}

.tab-content {
    display: none;
    margin-top: 20px;
    padding: 20px;
    background-color: var(--bg-secondary);
    border-radius: 6px;
    min-height: 200px;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

@media (max-width: 768px) {
    .tab-content {
        margin-top: 15px;
        padding: 15px;
        min-height: 150px;
    }
}

@media (max-width: 480px) {
    .tab-content {
        margin-top: 12px;
        padding: 12px;
        min-height: 120px;
        border-radius: 6px;
    }
}

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

.tab-content table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 10px;
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

@media (min-width: 769px) {
    .tab-content table {
        display: table;
    }
}

.tab-content table th,
.tab-content table td {
    padding: 12px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
    white-space: nowrap;
}

@media (max-width: 768px) {
    .tab-content table th,
    .tab-content table td {
        padding: 10px 8px;
        font-size: 0.9em;
    }
}

@media (max-width: 480px) {
    .tab-content table th,
    .tab-content table td {
        padding: 8px 6px;
        font-size: 0.85em;
    }
}

.tab-content table th {
    background-color: var(--bg-tertiary);
    font-weight: 600;
}

.validation-errors {
    margin-top: 20px;
    padding: 15px;
    background-color: rgba(220, 53, 69, 0.1);
    border: 1px solid var(--error-color);
    border-radius: 6px;
    color: var(--error-color);
}

.validation-errors.hidden {
    display: none;
}

.validation-errors ul {
    margin-left: 20px;
    margin-top: 10px;
}

@media (max-width: 768px) {
    .validation-errors {
        margin-top: 15px;
        padding: 12px;
    }

    .validation-errors ul {
        margin-left: 15px;
        margin-top: 8px;
    }
}

@media (max-width: 480px) {
    .validation-errors {
        margin-top: 12px;
        padding: 10px;
        font-size: 0.9em;
    }

    .validation-errors ul {
        margin-left: 12px;
        margin-top: 6px;
    }
}

.drag-over {
    background-color: rgba(0, 102, 204, 0.1);
    border-color: var(--accent-color);
}

.cost-display {
    font-size: 1.3em;
    font-weight: 700;
    color: var(--accent-color);
    margin-top: 15px;
    padding: 15px;
    background-color: var(--accent-light);
    border-radius: 10px;
    border-left: 4px solid var(--accent-color);
    box-shadow: var(--shadow);
    display: flex;
    align-items: center;
    gap: 8px;
}

.cost-display::before {
    content: '💰';
    font-size: 1.2em;
}

@media (max-width: 768px) {
    .cost-display {
        font-size: 1.2em;
        padding: 12px;
        margin-top: 12px;
    }
}

@media (max-width: 480px) {
    .cost-display {
        font-size: 1.1em;
        padding: 10px;
        margin-top: 10px;
        border-left-width: 3px;
    }
}