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

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --background: #f3f4f6;
    --surface: #ffffff;
    --border: #d1d5db;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --error: #ef4444;
    --success: #10b981;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --radius: 8px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.5;
    min-height: 100vh;
}

.app-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 20px;
}

.app-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.app-header > * {
    flex-shrink: 0;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    letter-spacing: -0.025em;
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 0.8125rem;
    font-weight: 500;
    padding: 4px 12px;
    background: var(--surface);
    border-radius: 20px;
    box-shadow: var(--shadow);
    white-space: nowrap;
}

.language-selector {
    margin-left: auto;
    display: flex;
    align-items: center;
}

.language-selector select {
    padding: 4px 8px;
    font-size: 0.8125rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    background: var(--surface);
    color: var(--text-primary);
    cursor: pointer;
}

.controls-section-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* 顶部栏：上传按钮 */
.top-bar {
    display: flex;
    align-items: center;
    margin-bottom: 20px;
}

.upload-area {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 8px 16px;
    cursor: pointer;
    transition: all 0.2s;
    background: var(--surface);
}

.upload-area:hover,
.upload-area.dragover {
    border-color: var(--primary-color);
    background-color: rgba(79, 70, 229, 0.05);
}

.upload-area .upload-icon {
    width: 18px;
    height: 18px;
    color: var(--text-secondary);
}

.upload-area .upload-text {
    font-size: 0.8125rem;
    color: var(--text-primary);
    font-weight: 500;
}

/* 预览区域 */
.preview-section {
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 16px;
    margin-bottom: 20px;
}

.preview-container {
    position: relative;
    height: min(50vh, 800px);
    background-color: #e5e7eb;
    background-image:
        linear-gradient(45deg, #d1d5db 25%, transparent 25%),
        linear-gradient(-45deg, #d1d5db 25%, transparent 25%),
        linear-gradient(45deg, transparent 75%, #d1d5db 75%),
        linear-gradient(-45deg, transparent 75%, #d1d5db 75%);
    background-size: 16px 16px;
    background-position: 0 0, 0 8px, 8px -8px, -8px 0;
    border-radius: var(--radius);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.placeholder-message {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    color: var(--text-secondary);
}

.preview-icon {
    width: 48px;
    height: 48px;
}

.placeholder-message p {
    font-size: 0.875rem;
}

#previewCanvas {
    max-width: 100%;
    max-height: 70vh;
    display: none;
}

#previewCanvas.visible {
    display: block;
}

/* 控制面板区域 */
.controls-area {
    background: var(--surface);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 20px;
}

.controls-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 16px;
    align-items: end;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.control-group label {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

.control-group input[type="text"],
.control-group select {
    width: 100%;
    padding: 6px 10px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 0.875rem;
    transition: border-color 0.2s;
}

.control-group input[type="text"]:focus,
.control-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.control-group input[type="range"] {
    width: 100%;
    height: 4px;
    -webkit-appearance: none;
    appearance: none;
    background: var(--border);
    border-radius: 2px;
    outline: none;
}

.control-group input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 14px;
    height: 14px;
    background: var(--primary-color);
    border-radius: 50%;
    cursor: pointer;
    transition: background 0.2s;
}

.control-group input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--primary-hover);
}

.range-value {
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--text-primary);
}

.color-picker-wrapper {
    display: flex;
    gap: 6px;
    align-items: center;
}

.color-picker-wrapper input[type="color"] {
    width: 32px;
    height: 32px;
    padding: 2px;
    border: 1px solid var(--border);
    border-radius: 6px;
    cursor: pointer;
}

.color-picker-wrapper input[type="text"] {
    flex: 1;
}

.output-actions {
    display: flex;
    align-items: end;
    gap: 12px;
}

.output-actions .control-group {
    flex: 0 0 auto;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 8px 20px;
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 6px;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
    height: fit-content;
}

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

.btn-primary:hover:not(:disabled) {
    background-color: var(--primary-hover);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.controls-section {
    padding-top: 16px;
    border-top: 1px solid var(--border);
    margin-top: 16px;
}

.controls-section:disabled {
    opacity: 0.5;
    pointer-events: none;
}

.error-message {
    margin-top: 8px;
    padding: 6px 12px;
    background-color: rgba(239, 68, 68, 0.1);
    border-radius: var(--radius);
    color: var(--error);
    font-size: 0.8125rem;
    display: none;
}

.error-message.visible {
    display: block;
}

.loading-indicator {
    display: none;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 24px;
    color: var(--text-secondary);
}

.loading-indicator.visible {
    display: flex;
}

.spinner {
    width: 32px;
    height: 32px;
    border: 3px solid var(--border);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

@media (max-width: 768px) {
    .app-header {
        flex-direction: column;
        text-align: center;
        gap: 4px;
    }

    .app-header h1 {
        justify-content: center;
    }

    .controls-grid {
        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    }

    .output-actions {
        flex-wrap: wrap;
    }
}

/* 帮助按钮 */
.help-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 28px;
    border: none;
    border-radius: 50%;
    background: var(--surface);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    box-shadow: var(--shadow);
    flex-shrink: 0;
}

.help-btn:hover {
    color: var(--primary-color);
    background: rgba(79, 70, 229, 0.05);
}

.help-btn svg {
    width: 16px;
    height: 16px;
}

/* 弹窗 */
.modal-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 20px;
}

.modal-overlay.visible {
    display: flex;
}

.modal-content {
    background: var(--surface);
    border-radius: 12px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
    max-width: 480px;
    width: 100%;
    animation: modalIn 0.25s ease-out;
}

@keyframes modalIn {
    from {
        opacity: 0;
        transform: translateY(16px) scale(0.96);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px 0;
}

.modal-header h3 {
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-primary);
}

.modal-close {
    width: 32px;
    height: 32px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: none;
    background: none;
    color: var(--text-secondary);
    font-size: 1.25rem;
    cursor: pointer;
    border-radius: 6px;
    transition: all 0.2s;
}

.modal-close:hover {
    background: var(--background);
    color: var(--text-primary);
}

.modal-body {
    padding: 20px 24px 24px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.help-item {
    display: flex;
    gap: 16px;
    align-items: flex-start;
}

.help-icon {
    flex-shrink: 0;
    width: 44px;
    height: 44px;
    border-radius: 10px;
    background: rgba(79, 70, 229, 0.08);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
}

.help-icon svg {
    width: 22px;
    height: 22px;
}

.help-text h4 {
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.help-text p {
    font-size: 0.8125rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Footer */
.app-footer {
    margin-top: 32px;
    padding-top: 16px;
    border-top: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 0.8125rem;
    color: var(--text-secondary);
}

.app-footer .footer-links,
.app-footer .footer-copy {
    display: flex;
    align-items: center;
    gap: 16px;
}

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

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

@media (max-width: 768px) {
    .app-footer {
        flex-direction: column;
        gap: 8px;
        text-align: center;
    }
}