:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #0f172a;
  --muted: #64748b;
  --border: #e6e8eb;
  --card: #ffffff;
  --elev: 0 1px 3px rgba(16,24,40,0.06);
  --primary: #0d6efd;
  --primary-600: #0b5ed7;
  --success: #22c55e;
  --success-600: #16a34a;
  --accent: #94a3b8;
  --ring: 0 0 0 3px rgba(13,110,253,.25);
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b1220;
    --fg: #e5e7eb;
    --muted: #a0aec0;
    --border: #374151;
    --card: #111827;
    --elev: 0 1px 3px rgba(0,0,0,.3);
    --primary: #2563eb;
    --primary-600: #1d4ed8;
    --success: #16a34a;
    --success-600: #15803d;
    --accent: #475569;
    --ring: 0 0 0 3px rgba(37,99,235,.35);
  }
}
* { box-sizing: border-box; }
body {
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  margin: 0; padding: 1rem;
  max-width: 980px; margin-inline: auto;
  background: var(--bg);
  color: var(--fg);
}
/* App header */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: .75rem;
  padding: .9rem 1rem;
  margin-block-end: 1rem;
  background: linear-gradient(180deg, rgba(148,163,184,0.08), transparent);
  border: 1px solid var(--border);
  border-radius: 14px;
}
.app-title {
  display: flex;
  align-items: center;
  gap: .75rem;
}
.app-icon {
  width: 36px; height: 36px;
  display: grid; place-items: center;
  border-radius: 10px;
  background: #e2e8f0;
}
@media (prefers-color-scheme: dark) {
  .app-icon { background: #1f2937; }
}
.header-actions { display: none; }
h1 { font-size: 1.25rem; margin: 0 0 .25rem; }
p { margin: 0; opacity: .8; color: var(--muted); }
.row { display: flex; gap: .75rem; flex-wrap: wrap; align-items: center; }
label { font-size: .9rem; opacity: .9; }
input[type="text"] {
  padding: .5rem .6rem; font-size: .95rem; min-width: 220px;
}
input[type="file"] {
  font-size: .95rem;
}
textarea {
  width: 100%; min-height: 50vh; resize: vertical;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: .95rem; line-height: 1.4;
  padding: .75rem; margin-block: .75rem;
  tab-size: 4; white-space: pre;
}
.controls {
  display: flex; gap: 1rem; align-items: center; flex-wrap: wrap;
  margin-block: .5rem 1rem;
}
.spacer { flex: 1; }
button {
  padding: .6rem .9rem; font-size: .95rem; font-weight: 600; cursor: pointer;
  border-radius: 8px;
}
button:focus-visible { outline: none; box-shadow: var(--ring); }
small.hint { display: block; opacity: .7; margin-top: .25rem; }
.note { font-size: .85rem; opacity: .8; }
.group { display: inline-flex; gap: .5rem; align-items: center; }
.error-line {
  background-color: #ffebee;
  border-left: 4px solid #f44336;
  padding-left: 8px;
}
@media (prefers-color-scheme: dark) {
  .error-line {
    background-color: #3d1a1a;
    border-left-color: #ff6b6b;
  }
}
.validation-message {
  color: #f44336;
  font-size: 0.85rem;
  margin-top: 0.5rem;
  padding: 0.5rem;
  background-color: #ffebee;
  border-radius: 4px;
  border-left: 4px solid #f44336;
  display: none;
  transition: all 0.2s ease-in-out;
}

.validation-message.immediate {
  animation: slideIn 0.2s ease-in-out;
  border-left-color: #ff9800;
  background-color: #fff3e0;
  color: #f57c00;
}

.validation-message.persistent {
  border-left-color: #f44336;
  background-color: #ffebee;
  color: #f44336;
}

@keyframes slideIn {
  0% {
    opacity: 0;
    transform: translateY(-10px);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (prefers-color-scheme: dark) {
  .validation-message {
    color: #ff6b6b;
    background-color: #3d1a1a;
    border-left-color: #ff6b6b;
  }
  
  .validation-message.immediate {
    background-color: #4a2c2a;
    color: #ffb74d;
    border-left-color: #ff9800;
  }
  
  .validation-message.persistent {
    background-color: #3d1a1a;
    color: #ff6b6b;
    border-left-color: #ff6b6b;
  }
}
button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}
.editor-container {
  position: relative;
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  margin-block: .75rem;
  background: var(--card);
  box-shadow: var(--elev);
}
.editor-wrapper {
  display: flex;
  min-height: 50vh;
}
.line-numbers {
  background-color: #f8fafc;
  border-right: 1px solid var(--border);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: 0.95rem;
  line-height: 1.4;
  padding: 0.75rem 0.5rem 0.75rem 0.25rem;
  color: #6b7280;
  user-select: none;
  min-width: 52px;
  text-align: right;
  white-space: pre;
  overflow: hidden;
}
@media (prefers-color-scheme: dark) {
  .line-numbers { background-color: #0f172a; color: #94a3b8; }
}
.line-numbers .error {
  background-color: #fee;
  color: #dc3545;
  font-weight: bold;
  animation: errorPulse 0.3s ease-in-out;
  border-radius: 2px;
  margin: 1px 0;
}

.line-numbers .error.immediate {
  background-color: #ffebee;
  border-left: 3px solid #f44336;
  padding-left: 2px;
  animation: immediateError 0.2s ease-in-out;
}

@keyframes errorPulse {
  0% { background-color: #fee; }
  50% { background-color: #ffcdd2; }
  100% { background-color: #fee; }
}

@keyframes immediateError {
  0% {
    background-color: #fff;
    transform: translateX(0);
  }
  50% {
    background-color: #ffebee;
    transform: translateX(2px);
  }
  100% {
    background-color: #ffebee;
    transform: translateX(0);
  }
}

@media (prefers-color-scheme: dark) {
  .line-numbers .error {
    background-color: #5d1a1a;
    color: #ff6b6b;
  }
  
  .line-numbers .error.immediate {
    background-color: #3d1a1a;
    border-left-color: #ff6b6b;
  }
  
  @keyframes errorPulse {
    0% { background-color: #5d1a1a; }
    50% { background-color: #7d2a2a; }
    100% { background-color: #5d1a1a; }
  }
  
  @keyframes immediateError {
    0% {
      background-color: #2d3748;
      transform: translateX(0);
    }
    50% {
      background-color: #3d1a1a;
      transform: translateX(2px);
    }
    100% {
      background-color: #3d1a1a;
      transform: translateX(0);
    }
  }
}
.editor-textarea {
  flex: 1;
  border: none;
  outline: none;
  resize: none;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: 0.95rem;
  line-height: 1.4;
  padding: 0.75rem 0.75rem 0.75rem 0.5rem;
  tab-size: 4;
  white-space: pre;
  background: transparent;
  color: inherit;
  margin: 0;
}
.options-left, .options-right {
  display: grid;
  gap: .75rem;
}
.options-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(200px, 1fr));
  gap: .5rem .75rem;
  align-items: center;
}
.option-tile {
  display: flex;
  align-items: center;
  gap: .5rem;
  padding: .5rem .6rem;
  border: 1px solid #eef0f2;
  border-radius: 8px;
  background: #fafafa;
}
@media (prefers-color-scheme: dark) {
  .option-tile {
    border-color: #374151;
    background: #111827;
  }
}
.options-actions {
  display: flex;
  gap: .5rem;
  align-items: center;
  flex-wrap: wrap;
  justify-content: flex-end;
}
.subtle {
  opacity: .8;
}
.btn {
  padding: .5rem .75rem;
  font-size: .9rem;
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: 10px;
  cursor: pointer;
  transition: background .15s ease, box-shadow .15s ease, transform .06s ease;
  color: var(--fg);
}
.btn:hover { background: #f3f4f6; box-shadow: 0 1px 2px rgba(16,24,40,.06); }
.btn:active { transform: translateY(1px); }
@media (prefers-color-scheme: dark) {
  .btn:hover { background: #0f172a; }
}
.btn.primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn.primary:hover { background: var(--primary-600); box-shadow: 0 2px 6px rgba(13,110,253,.24); }
.btn.success { background: var(--success); border-color: var(--success); color: #fff; }
.btn.success:hover { background: var(--success-600); }
.btn.ghost { background: transparent; border-color: var(--border); color: var(--fg); }
.btn.soft { filter: saturate(115%); }
.btn.xs { padding: .25rem .5rem; font-size: .8rem; border-radius: 6px; }
.file-input {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .45rem .6rem;
  border: 1px dashed #e6e8eb;
  border-radius: 8px;
  background: #ffffff;
}
@media (prefers-color-scheme: dark) {
  .btn { background: #111827; border-color: #374151; color: #e5e7eb; }
  .btn:hover { background: #0b1220; }
  .btn.primary { background: #2563eb; border-color: #2563eb; }
  .btn.primary:hover { background: #1d4ed8; }
  .btn.success { background: #16a34a; border-color: #16a34a; }
  .file-input { background: #111827; border-color: #374151; }
  .subtle { color: #d1d5db; }
}
@media (max-width: 780px) {
  .options-grid { grid-template-columns: 1fr; }
  .options-row { grid-template-columns: 1fr; }
  .options-actions { justify-content: flex-start; }
}
.csv-stats {
  background: #e8f2ff;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: .6rem .75rem;
  margin: .75rem 0;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  gap: .75rem;
  box-shadow: var(--elev);
}
.is-hidden { display: none !important; }
.tips-section {
  background: #fff3cd;
  border-left: 4px solid #ffc107;
  border-radius: 4px;
  padding: 1rem;
  margin-top: 1rem;
  font-size: 0.9rem;
}
.tips-section h4 {
  margin: 0 0 0.5rem;
  color: #856404;
}
.tips-section ul {
  margin: 0;
  padding-left: 1.5rem;
  color: #856404;
}
.csv-preview {
  margin: 0.75rem 0;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
  box-shadow: var(--elev);
  padding: .5rem .5rem .75rem;
}
.csv-preview h4 {
  margin: .5rem .5rem .5rem;
  font-size: 0.95rem;
  color: var(--fg);
}
.preview-table-wrap {
  overflow-x: auto;
  max-height: 300px;
  border: 1px solid var(--border);
  border-radius: 8px;
}
.preview-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
  background: white;
}
.preview-table th,
.preview-table td {
  border: 1px solid #ddd;
  padding: 0.5rem;
  text-align: left;
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.preview-table th {
  background-color: #f8f9fa;
  font-weight: 600;
  position: sticky;
  top: 0;
}
.preview-table tr:nth-child(even) {
  background-color: #f8f9fa;
}
@media (prefers-color-scheme: dark) {
  .ai-options {
    background-color: #2d3748;
  }
  .ai-options h3 {
    color: #e2e8f0;
  }
  .csv-stats {
    background-color: #1a365d;
    color: #bee3f8;
  }
  .csv-stats button {
    background: #3182ce !important;
  }
  .csv-preview h4 {
    color: #e2e8f0;
  }
  .preview-table {
    background: #2d3748;
    color: #e2e8f0;
  }
  .preview-table th {
    background-color: #4a5568;
  }
  .preview-table tr:nth-child(even) {
    background-color: #4a5568;
  }
  .preview-table th,
  .preview-table td {
    border-color: #4a5568;
  }
  .tips-section {
    background-color: #744210;
    border-left-color: #d69e2e;
  }
  .tips-section h4,
  .tips-section ul {
    color: #faf089;
  }
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  box-shadow: var(--elev);
}
.card h4 {
  margin: 0 0 .5rem;
  font-size: 1rem;
  color: var(--fg);
}
.section-subtle {
  margin-top: 1rem;
  color: var(--muted);
  font-weight: 700;
  letter-spacing: .01em;
  display: block;
  padding-top: .25rem;
}

/* Perfected spacing and grouping for the options card */
.card--options {
  padding: 1rem .95rem .95rem;
}
.card--options > h4 {
  margin: 0 0 .4rem;
  font-weight: 700;
  letter-spacing: .005em;
}
.card--options .options-grid:first-of-type {
  margin-top: .35rem;
}
.card--options .options-grid + .section-subtle {
  margin-top: 1rem;
  padding-top: .4rem;
  border-top: 1px solid var(--border);
}
.card--options .ai-cleanups {
  margin-top: .6rem;
  padding-top: 0;
  border-top: none;
}
.card--options .option-tile {
  padding: .5rem .65rem;
  gap: .5rem;
  border-radius: 10px;
}
.card--options .option-tile input[type="checkbox"] {
  inline-size: 16px;
  block-size: 16px;
}
.card--options .actions-row {
  margin-top: 1rem;
  gap: .5rem;
  justify-content: space-between;
}
@media (min-width: 640px) {
  .card--options .actions-row { justify-content: flex-end; }
}

.control-panel {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 1rem;
  margin-block: .5rem 1rem;
}
.ai-cleanups {
  margin-top: 1rem;                 /* space away from General Options */
  padding-top: .5rem;               /* internal top spacing */
  border-top: 1px solid var(--border); /* subtle divider */
}

.file-upload-area {
  display: flex;
  flex-direction: column;
  gap: .75rem;
}

.file-upload-button-wrapper {
  display: flex;
  align-items: center;
  gap: .5rem;
}

.file-upload-button {
  padding: .6rem .9rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  border: 1px solid #e6e8eb;
  background: #ffffff;
  border-radius: 8px;
  transition: background .15s ease, box-shadow .15s ease;
}
.file-upload-button:hover {
  background: #f3f4f6;
  box-shadow: 0 1px 2px rgba(16,24,40,.06);
}
@media (prefers-color-scheme: dark) {
  .file-upload-button {
    background: #111827;
    border-color: #374151;
    color: #e5e7eb;
  }
  .file-upload-button:hover { background: #0b1220; }
}

.filename-display {
  font-size: .9rem;
  opacity: .8;
  flex-grow: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: .6rem;
  margin-top: .5rem;
}
.option-tile {
  padding: .6rem .75rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--card);
}
.actions-row {
  display: flex;
  gap: .6rem;
  flex-wrap: wrap;
  justify-content: flex-end;
  margin-top: .75rem;
}