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

:root {
    --primary-color: #6366f1;
    --primary-hover: #4f46e5;
    --secondary-color: #8b5cf6;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.12);
    --gradient-1: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-2: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: var(--bg-color);
    color: var(--text-primary);
    min-height: 100vh;
}

/* Header */
.header {
    background: var(--card-bg);
    box-shadow: var(--shadow);
    padding: 1.5rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: baseline;
    gap: 0.75rem;
}

.logo h1 {
    font-size: 1.75rem;
    color: var(--text-primary);
    font-weight: 700;
}

.logo span {
    color: var(--primary-color);
    font-size: 1.25rem;
    font-weight: 600;
}

.back-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9375rem;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.back-link:hover {
    color: var(--primary-color);
}

/* Header Container */
.header .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

/* Hero Container */
.hero .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Main Layout */
.main-wrapper {
    max-width: 1200px;
    margin: 0 auto;
    padding: 3rem 2rem;
    display: grid;
    grid-template-columns: 320px 1fr;
    gap: 2rem;
    align-items: start;
}

/* Sidebar */
.sidebar {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.card {
    background: var(--card-bg);
    border-radius: 16px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

.card h2 {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 500;
}

/* Mode Selection */
.mode-tabs {
    display: flex;
    gap: 0.5rem;
}

.mode-tab {
    flex: 1;
    padding: 0.875rem 1rem;
    border: none;
    border-radius: 10px;
    background: transparent;
    cursor: pointer;
    font-size: 0.9375rem;
    transition: all 0.2s;
    color: var(--text-secondary);
}

.mode-tab.active {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

/* Operation Steps */
.steps-list {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    min-height: 100px;
}

.step-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.75rem;
    background: var(--bg-color);
    border-radius: 8px;
    cursor: grab;
}

.step-item.dragging {
    opacity: 0.5;
}

.step-drag {
    color: var(--text-secondary);
    cursor: grab;
}

.step-name {
    flex: 1;
    font-size: 0.875rem;
}

.step-remove {
    background: none;
    border: none;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 4px;
}

.step-remove:hover {
    background: #fee2e2;
    color: #ef4444;
}

.add-step-btn {
    width: 100%;
    padding: 0.75rem;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    font-size: 0.875rem;
    transition: all 0.2s;
}

.add-step-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.steps-menu {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.625rem;
    margin-top: 1rem;
}

.step-option {
    padding: 0.875rem 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    background: transparent;
    cursor: pointer;
    font-size: 0.875rem;
    transition: all 0.2s;
    color: var(--text-primary);
    text-align: center;
}

.step-option:hover {
    border-color: var(--primary-color);
    background: rgba(99, 102, 241, 0.05);
    color: var(--primary-color);
}

.step-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 0.875rem;
    background: #f8fafc;
    border-radius: 10px;
    cursor: grab;
    border: 1px solid transparent;
}

.step-item:hover {
    border-color: var(--border-color);
}

/* Main Content */
.main-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

/* Upload Area */
.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 16px;
    padding: 4rem 3rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s;
    background: var(--card-bg);
}

.upload-area:hover {
    border-color: var(--primary-color);
    background: #fafafa;
}

.upload-area.has-file {
    border-color: #10b981;
    border-style: solid;
    background: #f0fdf4;
}

.upload-icon {
    font-size: 3.5rem;
    margin-bottom: 1rem;
    opacity: 0.7;
}

.upload-text {
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    font-size: 1rem;
}

.upload-hint {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

#fileInput {
    display: none;
}

/* Preview Area */
.preview-section {
    display: none;
}

.preview-section.active {
    display: block;
}

.preview-container {
    background: var(--card-bg);
    border-radius: 16px;
    box-shadow: var(--shadow);
    padding: 1.5rem;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

.preview-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.25rem;
    padding-bottom: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.preview-title {
    font-size: 1rem;
    color: var(--text-primary);
    font-weight: 500;
}

.preview-info {
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.preview-image-container {
    display: flex;
    gap: 1.5rem;
    justify-content: center;
    flex-wrap: wrap;
}

.preview-box {
    flex: 1;
    min-width: 300px;
    text-align: center;
}

.preview-box h3 {
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 500;
}

.preview-box img {
    max-width: 100%;
    max-height: 400px;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

/* Settings Panel */
.settings-panel {
    display: none;
}

.settings-panel.active {
    display: block;
}

.setting-step {
    padding-bottom: 1.5rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

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

.settings-panel h2 {
    font-size: 0.9375rem;
    color: var(--text-primary);
    margin-bottom: 1.25rem;
    font-weight: 600;
}

.setting-group {
    margin-bottom: 1.25rem;
}

.setting-group label {
    display: block;
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.setting-group input[type="range"] {
    width: 100%;
    height: 6px;
    -webkit-appearance: none;
    background: var(--border-color);
    border-radius: 3px;
    outline: none;
}

.setting-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 6px rgba(99, 102, 241, 0.3);
}

.setting-group input[type="number"],
.setting-group input[type="text"],
.setting-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 10px;
    font-size: 0.9375rem;
    transition: all 0.2s;
}

.setting-group input[type="number"]:focus,
.setting-group input[type="text"]:focus,
.setting-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

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

.range-value {
    text-align: right;
    font-size: 0.875rem;
    color: var(--primary-color);
    font-weight: 500;
}

/* Action Buttons */
.action-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    padding-top: 0.5rem;
}

.btn {
    padding: 0.875rem 2.5rem;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 500;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
    background: var(--primary-hover);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.btn-primary:disabled {
    background: var(--border-color);
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

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

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

/* Hero Section */
.hero {
    background: var(--gradient-2);
    color: white;
    padding: 4rem 0 3rem;
    text-align: center;
}

.hero-title {
    font-size: 2.25rem;
    font-weight: 700;
    margin-bottom: 1rem;
    animation: fadeInUp 0.6s ease-out;
}

.hero-subtitle {
    font-size: 1.125rem;
    opacity: 0.95;
    margin-bottom: 1rem;
    animation: fadeInUp 0.6s ease-out 0.1s both;
}

.hero-description {
    font-size: 1rem;
    max-width: 700px;
    margin: 0 auto;
    opacity: 0.9;
    line-height: 1.8;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Footer */
.footer {
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
    padding: 2rem 0;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-top: 3rem;
}

.footer .footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 2rem;
    margin-bottom: 1rem;
}

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.2s ease;
}

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

/* Loading */
.loading {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading.active {
    display: flex;
}

.loading-spinner {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
}

.spinner {
    width: 50px;
    height: 50px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Canvas (hidden) */
#canvas {
    display: none;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .main-wrapper {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        order: 2;
    }
    
    .main-content {
        order: 1;
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 1.75rem;
    }
    
    .hero-subtitle {
        font-size: 1rem;
    }
    
    .hero-description {
        font-size: 0.9375rem;
    }
    
    .header .container,
    .hero .container {
        padding: 0 1rem;
    }
    
    .main-wrapper {
        padding: 2rem 1rem;
    }
    
    .footer .footer-content {
        padding: 0 1rem;
    }
    
    .preview-image-container {
        flex-direction: column;
    }
    
    .setting-row {
        grid-template-columns: 1fr;
    }
    
    .footer-links {
        flex-direction: column;
        gap: 0.75rem;
    }
}

@media (max-width: 480px) {
    .hero {
        padding: 3rem 0 2rem;
    }
    
    .hero-title {
        font-size: 1.5rem;
    }
    
    .logo h1 {
        font-size: 1.5rem;
    }
    
    .logo span {
        font-size: 1rem;
    }
    
    .back-link {
        font-size: 0.875rem;
    }
}