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

:root {
  --bg: #ffffff;
  --surface: #f8fafc;
  --surface-2: #f0f2f5;
  --border: #e0e2e6;
  --text: #181d26;
  --text-weak: rgba(4, 14, 32, 0.69);
  --text-muted: rgba(4, 14, 32, 0.45);
  --primary: #1b61c9;
  --primary-hover: #254fad;
  --primary-light: rgba(27, 97, 201, 0.08);
  --success: #006400;
  --accent: #254fad;
  --shadow-blue: rgba(0,0,0,0.32) 0px 0px 1px, rgba(0,0,0,0.08) 0px 0px 2px, rgba(45,127,249,0.28) 0px 1px 3px, rgba(0,0,0,0.06) 0px 0px 0px 0.5px inset;
  --shadow-soft: rgba(15, 48, 106, 0.05) 0px 0px 20px;
  --radius-btn: 12px;
  --radius-card: 16px;
  --radius-lg: 24px;
}

body {
  font-family: 'Haas', -apple-system, system-ui, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  letter-spacing: 0.08px;
}

#app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

header {
  text-align: center;
  padding: 40px 0 28px;
}

header h1 {
  font-size: 32px;
  font-weight: 400;
  letter-spacing: normal;
  color: var(--text);
}

header h1 span {
  color: var(--primary);
  font-weight: 900;
}

.subtitle {
  color: var(--text-weak);
  font-size: 16px;
  margin-top: 8px;
  letter-spacing: 0.18px;
}

/* Step Indicator */
.steps {
  margin-bottom: 32px;
}

.step-indicator {
  display: flex;
  justify-content: center;
  gap: 4px;
}

.step-dot {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text-weak);
  padding: 8px 18px;
  border-radius: 99px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 500;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  gap: 6px;
  letter-spacing: 0.07px;
}

.step-dot span {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--surface-2);
  font-size: 12px;
  font-weight: 600;
  color: var(--text-weak);
}

.step-dot.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
  box-shadow: var(--shadow-blue);
}

.step-dot.active span {
  background: rgba(255, 255, 255, 0.2);
  color: white;
}

.step-dot.completed {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-light);
}

.step-dot.completed span {
  background: var(--primary);
  color: white;
}

/* Step Panels */
.step-panel {
  display: none;
}

.step-panel.active {
  display: block;
  animation: fadeIn 0.25s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.step-panel h2 {
  font-size: 24px;
  font-weight: 400;
  margin-bottom: 4px;
  color: var(--text);
}

.step-desc {
  color: var(--text-weak);
  font-size: 15px;
  margin-bottom: 24px;
  letter-spacing: 0.1px;
}

.step-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
}

/* Buttons */
.btn {
  padding: 10px 24px;
  border-radius: var(--radius-btn);
  border: none;
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  letter-spacing: 0.08px;
}

.btn:disabled {
  opacity: 0.38;
  cursor: not-allowed;
}

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

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

.btn-secondary {
  background: white;
  color: var(--text);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-soft);
}

.btn-secondary:hover {
  background: var(--surface);
  border-color: #c8ccd4;
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.9);
  color: var(--text);
  border: 1px solid var(--border);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
  box-shadow: var(--shadow-soft);
}

.btn-icon:hover {
  background: white;
  box-shadow: var(--shadow-blue);
}

.btn-export {
  width: 100%;
  padding: 12px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: var(--radius-btn);
  font-size: 15px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  letter-spacing: 0.08px;
  box-shadow: var(--shadow-blue);
}

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

.btn-export:disabled {
  opacity: 0.38;
  cursor: not-allowed;
}

/* Template Grid */
.template-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
  margin-bottom: 16px;
}

.template-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 14px;
  cursor: pointer;
  transition: all 0.15s;
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

.template-card:hover {
  border-color: #c0c8d6;
  box-shadow: var(--shadow-blue);
  transform: translateY(-1px);
}

.template-card.selected {
  border-color: var(--primary);
  background: var(--primary-light);
  box-shadow: var(--shadow-blue);
}

.template-card.selected::after {
  content: '';
  position: absolute;
  top: 10px;
  right: 10px;
  width: 20px;
  height: 20px;
  background: var(--primary);
  border-radius: 50%;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='white' stroke-width='3'%3E%3Cpolyline points='20 6 9 17 4 12'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: center;
}

.template-preview {
  height: 120px;
  background: #181d26;
  border-radius: 10px;
  margin-bottom: 12px;
  overflow: hidden;
  position: relative;
}

.template-preview canvas {
  width: 100%;
  height: 100%;
}

.template-name {
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 3px;
  color: var(--text);
  letter-spacing: 0.07px;
}

.template-desc {
  font-size: 12px;
  color: var(--text-weak);
  letter-spacing: 0.07px;
  line-height: 1.4;
}

.template-tags {
  display: flex;
  gap: 4px;
  margin-top: 8px;
  flex-wrap: wrap;
}

.template-tag {
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 99px;
  background: var(--surface-2);
  color: var(--text-weak);
  border: 1px solid var(--border);
  letter-spacing: 0.07px;
}

.upload-thumb {
  position: relative;
  aspect-ratio: 16/10;
  border-radius: 10px;
  overflow: hidden;
  background: var(--surface-2);
  border: 1px solid var(--border);
  box-shadow: var(--shadow-soft);
}

.upload-thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.upload-thumb .remove-btn {
  position: absolute;
  top: 4px;
  right: 4px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: rgba(24, 29, 38, 0.7);
  border: none;
  color: white;
  font-size: 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity 0.15s;
}

.upload-thumb:hover .remove-btn {
  opacity: 1;
}

[hidden] {
  display: none !important;
}

.compression-info {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  font-size: 13px;
  color: var(--text-weak);
  margin-bottom: 12px;
  letter-spacing: 0.07px;
}

.compression-info svg {
  color: var(--text-muted);
  flex-shrink: 0;
}

.savings {
  color: var(--success);
  font-weight: 500;
}

/* Preview Layout */
.preview-layout {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.preview-container {
  position: relative;
  background: #181d26;
  border-radius: var(--radius-card);
  overflow: hidden;
  border: 1px solid var(--border);
  box-shadow: var(--shadow-blue);
}

.preview-container canvas {
  width: 100%;
  display: block;
  aspect-ratio: 16/9;
}

.preview-controls {
  position: absolute;
  bottom: 12px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 8px;
}

.config-section {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  padding: 20px;
}

/* Configuration Tabs */
.config-tabs-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  overflow: hidden;
}

.config-tabs-header {
  display: flex;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  overflow-x: auto;
  scrollbar-width: none;
}
.config-tabs-header::-webkit-scrollbar { display: none; }

.config-tab {
  padding: 14px 24px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text-muted);
  background: transparent;
  border: none;
  border-bottom: 2px solid transparent;
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.2s;
  outline: none;
}

.config-tab:hover {
  color: var(--text);
  background: rgba(255, 255, 255, 0.02);
}

.config-tab.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  background: var(--surface);
}

.config-tab-pane {
  display: none;
}

.config-tab-pane.active {
  display: block;
}

.config-group {
  margin-bottom: 16px;
}

.config-group:last-child {
  margin-bottom: 0;
}

.config-group > label:not(.toggle) {
  display: block;
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.config-group select,
.config-group input[type="text"] {
  width: 100%;
  padding: 8px 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 13px;
  outline: none;
  transition: border-color 0.15s;
  letter-spacing: 0.07px;
}

.config-group select:focus,
.config-group input[type="text"]:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(27, 97, 201, 0.12);
}

.config-group input[type="range"] {
  width: 100%;
  -webkit-appearance: none;
  height: 3px;
  background: var(--border);
  border-radius: 2px;
  outline: none;
  margin-top: 6px;
}

.config-group input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  background: var(--primary);
  border-radius: 50%;
  cursor: pointer;
  box-shadow: 0 0 0 3px rgba(27, 97, 201, 0.15);
}

.range-val {
  display: inline-block;
  font-size: 12px;
  color: var(--primary);
  font-weight: 500;
  margin-top: 3px;
  letter-spacing: 0.07px;
}

.color-input-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

.color-input-row input[type="color"] {
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
  background: var(--bg);
  cursor: pointer;
}

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

.border-config {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

/* Export */
.export-layout {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: 16px;
  align-items: start;
}

.export-options {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 18px;
  box-shadow: var(--shadow-soft);
}

.format-toggle, .quality-toggle {
  display: flex;
  gap: 3px;
  background: var(--surface);
  padding: 3px;
  border-radius: 10px;
  border: 1px solid var(--border);
}

.fmt-btn, .qual-btn {
  flex: 1;
  padding: 8px;
  border: none;
  border-radius: 8px;
  background: transparent;
  color: var(--text-weak);
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.07px;
}

.fmt-btn.active, .qual-btn.active {
  background: white;
  color: var(--primary);
  box-shadow: var(--shadow-blue);
  font-weight: 500;
}

.quality-desc {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 6px;
  letter-spacing: 0.07px;
}

.export-estimate {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  margin: 14px 0;
}

.estimate-row {
  display: flex;
  justify-content: space-between;
  font-size: 13px;
  padding: 3px 0;
  letter-spacing: 0.07px;
}

.estimate-row span:first-child {
  color: var(--text-weak);
}

.estimate-row span:last-child {
  font-weight: 500;
  color: var(--text);
}

.export-progress {
  margin-top: 12px;
}

.progress-bar {
  height: 4px;
  background: var(--surface-2);
  border-radius: 2px;
  overflow: hidden;
  margin-bottom: 8px;
}

.progress-fill {
  height: 100%;
  background: var(--primary);
  border-radius: 2px;
  width: 0%;
  transition: width 0.2s;
}

.progress-text {
  font-size: 12px;
  color: var(--text-weak);
  letter-spacing: 0.07px;
}

.export-result {
  margin-top: 12px;
  padding: 12px;
  background: rgba(0, 100, 0, 0.05);
  border: 1px solid rgba(0, 100, 0, 0.18);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.result-info {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

#result-filename {
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
  letter-spacing: 0.07px;
}

#result-size {
  font-size: 12px;
  color: var(--text-weak);
}

.export-preview-wrap {
  background: #181d26;
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  overflow: hidden;
  box-shadow: var(--shadow-blue);
}

.export-preview-wrap canvas {
  width: 100%;
  display: block;
  aspect-ratio: 16/9;
}

/* Row Config Section (Upload step) */
.row-config-section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-card);
  padding: 14px 16px;
  margin-bottom: 12px;
}

.row-config-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.row-config-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 500;
  color: var(--text);
}

.row-count-badge {
  background: var(--primary);
  color: white;
  font-size: 11px;
  font-weight: 600;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.row-count-stepper {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px 6px;
}

.row-count-stepper span {
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  min-width: 16px;
  text-align: center;
}

.stepper-btn {
  width: 24px;
  height: 24px;
  border-radius: 6px;
  border: none;
  background: var(--surface-2);
  color: var(--text);
  font-size: 16px;
  line-height: 1;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.stepper-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

/* Row Types */
.row-type-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.row-type-item {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  transition: all 0.15s;
  cursor: default;
}

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

.row-type-item:hover {
  background: var(--bg);
}

.row-type-item.dragging {
  opacity: 0.4;
}

.row-type-item.drag-over {
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(27, 97, 201, 0.1);
}

.row-upload-area {
  border: 1.5px dashed var(--border);
  border-radius: 8px;
  padding: 24px;
  text-align: center;
  cursor: pointer;
  transition: all 0.15s;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}

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

.row-upload-area p {
  color: var(--text-weak);
  font-size: 13px;
  letter-spacing: 0.07px;
}

.row-upload-preview {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: 8px;
}

.row-upload-preview .upload-thumb {
  aspect-ratio: 16/10;
}

.drag-handle {
  color: var(--text-muted);
  cursor: grab;
  display: flex;
  align-items: center;
  flex-shrink: 0;
  padding: 2px;
  border-radius: 4px;
  transition: color 0.12s;
}

.drag-handle:hover {
  color: var(--primary);
}

.drag-handle:active {
  cursor: grabbing;
}

.row-type-label {
  font-size: 12px;
  color: var(--text-weak);
  letter-spacing: 0.07px;
  white-space: nowrap;
  flex: 1;
}

.row-type-toggle {
  display: flex;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 2px;
  gap: 2px;
}

.row-type-btn {
  padding: 4px 10px;
  border: none;
  border-radius: 6px;
  background: transparent;
  color: var(--text-weak);
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  gap: 4px;
  letter-spacing: 0.07px;
}

.row-type-btn.active {
  background: white;
  color: var(--primary);
  box-shadow: var(--shadow-blue);
}

/* Seamless Duration UI */
.duration-auto {
  display: flex;
  flex-direction: column;
  gap: 10px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
}

.duration-computed,
.duration-total {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.duration-label {
  font-size: 12px;
  color: var(--text-weak);
  letter-spacing: 0.07px;
}

.duration-value {
  font-size: 14px;
  font-weight: 500;
  color: var(--primary);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.07px;
}

.loop-multiplier {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding-top: 2px;
}

.mult-btns {
  display: flex;
  gap: 3px;
}

.mult-btn {
  padding: 4px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: white;
  color: var(--text-weak);
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
  letter-spacing: 0.07px;
}

.mult-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: white;
  box-shadow: var(--shadow-blue);
}

.mult-btn:hover:not(.active) {
  border-color: var(--primary);
  color: var(--primary);
}

/* Footer */
footer {
  text-align: center;
  padding: 32px 24px;
  color: var(--text-muted);
  font-size: 13px;
}

footer a {
  color: var(--primary);
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

/* Responsive */
@media (max-width: 768px) {
  .preview-layout {
    grid-template-columns: 1fr;
  }

  .export-layout {
    grid-template-columns: 1fr;
  }

  .template-grid {
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  }

  .step-indicator {
    flex-wrap: wrap;
  }
}