:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #eef2ff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --bg: #ffffff;
  --bg-soft: #f8fafc;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(30, 41, 59, 0.08);
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 860px;
  margin: 0 auto;
  padding: 0 20px;
}

.hidden {
  display: none !important;
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  padding-bottom: 14px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text);
  font-weight: 800;
  font-size: 1.2rem;
}

.badge {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--primary-dark);
  background: var(--primary-light);
  padding: 6px 12px;
  border-radius: 999px;
  white-space: nowrap;
}

/* Hero */
.hero {
  text-align: center;
  padding: 56px 0 36px;
}

.hero h1 {
  font-size: clamp(1.8rem, 4.5vw, 2.6rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin-bottom: 16px;
}

.subtitle {
  color: var(--text-muted);
  font-size: 1.05rem;
  max-width: 640px;
  margin: 0 auto;
}

/* Tool card */
.tool-card {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

/* Upload area */
.upload-area {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 48px 24px;
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  text-align: center;
  color: var(--primary);
}

.upload-area:hover,
.upload-area.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.upload-title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text);
}

.upload-sub {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 8px;
}

/* Buttons */
.btn {
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  border: none;
  border-radius: 10px;
  padding: 10px 20px;
  cursor: pointer;
  transition: background 0.2s, transform 0.1s;
}

.btn:active {
  transform: scale(0.98);
}

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

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

.btn-lg {
  font-size: 1.05rem;
  padding: 14px 32px;
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.85rem;
}

.btn-ghost {
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border);
}

.btn-ghost:hover {
  background: var(--bg-soft);
  color: var(--text);
}

.btn-add {
  background: var(--primary-light);
  color: var(--primary-dark);
}

.btn-add:hover {
  background: #e0e7ff;
}

/* Editor */
.editor {
  margin-top: 24px;
}

.editor-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 24px;
  max-height: 320px;
  overflow-y: auto;
  padding-right: 4px;
}

.item {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 8px 12px;
  cursor: grab;
  user-select: none;
}

.item.dragging {
  opacity: 0.5;
  border-color: var(--primary);
}

.item .thumb {
  width: 48px;
  height: 48px;
  object-fit: cover;
  border-radius: 8px;
  flex-shrink: 0;
  background: var(--bg-soft);
}

.item .item-name {
  flex: 1;
  font-size: 0.85rem;
  color: var(--text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.item .item-size {
  font-size: 0.75rem;
  color: var(--text-muted);
  flex-shrink: 0;
}

.item .item-remove {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.1rem;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  flex-shrink: 0;
}

.item .item-remove:hover {
  color: #dc2626;
  background: #fef2f2;
}

/* Controls */
.controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 20px;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.control-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
}

.segmented {
  display: flex;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 3px;
  gap: 3px;
}

.seg-btn {
  flex: 1;
  font-family: inherit;
  font-size: 0.85rem;
  font-weight: 600;
  border: none;
  background: transparent;
  color: var(--text-muted);
  padding: 8px;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.seg-btn.active {
  background: var(--primary);
  color: #fff;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--primary);
}

.bg-row {
  display: flex;
  align-items: center;
  gap: 10px;
}

input[type="color"] {
  width: 48px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 2px;
  background: var(--bg);
  cursor: pointer;
}

/* Actions */
.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: center;
}

/* Result */
.result {
  margin-top: 28px;
  border-top: 1px solid var(--border);
  padding-top: 20px;
}

.result-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 14px;
}

.result-head h2 {
  font-size: 1.15rem;
}

.result-canvas-wrap {
  max-height: 500px;
  overflow: auto;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: repeating-conic-gradient(#f1f5f9 0% 25%, #fff 0% 50%) 50% / 20px 20px;
}

.result-canvas-wrap canvas {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
}

.result-note {
  margin-top: 10px;
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* SEO content */
.seo-content {
  padding: 56px 0 16px;
}

.seo-content h2 {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin: 32px 0 12px;
}

.seo-content p,
.seo-content li {
  color: var(--text-muted);
  margin-bottom: 12px;
}

.seo-content ul,
.seo-content ol {
  padding-left: 24px;
}

.seo-content strong {
  color: var(--text);
}

/* FAQ */
#faq {
  padding-bottom: 56px;
}

.faq-title {
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 24px;
}

.faq {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.faq details {
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg-soft);
  overflow: hidden;
}

.faq summary {
  padding: 14px 18px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.faq summary::after {
  content: '+';
  font-size: 1.2rem;
  color: var(--primary);
  transition: transform 0.2s;
}

.faq details[open] summary::after {
  transform: rotate(45deg);
}

.faq details p {
  padding: 0 18px 14px;
  color: var(--text-muted);
  font-size: 0.92rem;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-soft);
  padding: 28px 0;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  text-align: center;
}

.footer-inner p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 600px) {
  .tool-card {
    padding: 16px;
  }

  .badge {
    display: none;
  }

  .hero {
    padding: 40px 0 24px;
  }

  .actions .btn {
    flex: 1;
  }
}