:root {
  --bg: #f5f5f7;
  --panel: #f8f8fa;
  --card: #ffffff;
  --border: #e1e1e6;
  --border-strong: #d4d4d8;
  --ink: #1d1d1f;
  --muted: #636366;
  --muted-2: #87878c;
  --accent: #007aff;
  --accent-press: #0069dc;
  --warn: #b4781e;
  --error: #aa3232;
  --radius: 8px;
  --radius-lg: 12px;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.04), 0 4px 12px rgba(0, 0, 0, 0.04);
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", system-ui, sans-serif;
  font-size: 14px;
  line-height: 1.45;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

.topbar {
  display: flex;
  align-items: center;
  gap: 24px;
  background: #fcfcfe;
  border-bottom: 1px solid var(--border);
  padding: 10px 20px;
  padding-left: max(20px, env(safe-area-inset-left));
  padding-right: max(20px, env(safe-area-inset-right));
  padding-top: max(10px, env(safe-area-inset-top));
}
.topbar h1 { margin: 0; font-size: 17px; font-weight: 600; letter-spacing: -0.01em; }

.tabs { display: flex; gap: 4px; }
.tab {
  -webkit-appearance: none;
  appearance: none;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 5px 12px;
  font: inherit;
  color: var(--muted);
  cursor: pointer;
}
.tab:hover { background: rgba(0,0,0,0.04); }
.tab.is-active { background: #fff; color: var(--ink); border-color: var(--border); box-shadow: var(--shadow); }

.layout {
  display: grid;
  grid-template-columns: 340px 1fr;
  gap: 0;
  min-height: calc(100vh - 50px);
  min-height: calc(100dvh - 50px);
}

.controls {
  background: var(--panel);
  border-right: 1px solid var(--border);
  padding: 18px 20px;
  overflow-y: auto;
}
.controls section { margin-bottom: 22px; }
.controls h3 {
  font-size: 11px;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  margin: 0 0 10px;
}

label {
  display: block;
  font-size: 13px;
  color: var(--ink);
  margin-bottom: 10px;
}
label.block { display: block; margin-bottom: 14px; }
label.check { display: flex; align-items: center; gap: 8px; }

select, input[type="text"], input[type="number"], textarea {
  width: 100%;
  padding: 7px 10px;
  margin-top: 4px;
  background: var(--card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  font: inherit;
  color: var(--ink);
}
input[type="number"] { width: 80px; padding: 6px 8px; }
textarea { resize: vertical; min-height: 56px; overflow-wrap: anywhere; }
select:focus, input:focus, textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.18);
}

input[type="range"] { width: calc(100% - 40px); margin-top: 6px; vertical-align: middle; }
output { display: inline-block; margin-left: 8px; min-width: 28px; text-align: right; color: var(--muted); font-variant-numeric: tabular-nums; }

input[type="color"] {
  width: 36px;
  height: 26px;
  padding: 0;
  border: 1px solid var(--border-strong);
  border-radius: 6px;
  background: transparent;
  vertical-align: middle;
  cursor: pointer;
}

input[type="file"] {
  font: inherit;
  color: var(--muted);
}
input[type="file"]::file-selector-button {
  -webkit-appearance: none;
  appearance: none;
  background: var(--card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 6px 12px;
  font: inherit;
  color: var(--ink);
  margin-right: 10px;
  cursor: pointer;
}
input[type="file"]::file-selector-button:hover { background: #eef0f2; }

.row { display: flex; gap: 12px; align-items: center; flex-wrap: wrap; margin-bottom: 10px; }
.row > label { margin-bottom: 0; }

button {
  -webkit-appearance: none;
  appearance: none;
  background: var(--card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  padding: 8px 14px;
  font: inherit;
  color: var(--ink);
  cursor: pointer;
}
button:hover:not(:disabled) { background: #eef0f2; }
button:active:not(:disabled) { background: #dfe2e6; }
button:disabled { opacity: 0.5; cursor: not-allowed; }
button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  font-weight: 500;
  padding: 9px 18px;
}
button.primary:hover:not(:disabled) { background: var(--accent-press); border-color: var(--accent-press); }
button.ghost { background: transparent; border-color: var(--border); }

.pane { display: none; padding: 24px 28px; }
.pane.is-active { display: block; }

.preview-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 16px auto;
  max-width: 560px;
  box-shadow: var(--shadow);
}
#preview {
  display: block;
  width: 100%;
  max-width: 480px;
  height: auto;
  image-rendering: pixelated;
  image-rendering: -moz-crisp-edges;
}
#preview:not([src]) { display: none; }

.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
  margin: 12px 0 16px;
  box-shadow: var(--shadow);
}

.status { color: var(--muted); margin: 8px 0; min-height: 1em; }
.warn { color: var(--warn); margin: 8px 0; font-size: 13px; }
.muted { color: var(--muted); }
.hint { color: var(--muted-2); font-size: 11.5px; margin: 4px 0 8px; }

#single-pane { max-width: 720px; margin: 0 auto; }
#batch-pane { max-width: 720px; margin: 0 auto; }
#batch-pane h2 { font-size: 18px; font-weight: 600; margin: 8px 0 4px; }

progress { width: 100%; height: 8px; }

.error-item { color: var(--error); font-size: 12.5px; }

@media (max-width: 760px) {
  .layout { grid-template-columns: 1fr; }
  .controls { border-right: none; border-bottom: 1px solid var(--border); max-height: 50vh; }
  .pane { padding: 18px 16px; }
  .topbar { padding: 10px 16px; gap: 14px; }

  /* Prevent iOS Safari zoom-on-focus by keeping form text ≥16px on small screens. */
  select, input[type="text"], input[type="number"], input[type="search"],
  input[type="email"], input[type="url"], input[type="tel"], textarea {
    font-size: 16px;
  }

  /* Bump tap targets toward the 44px Apple HIG / 48dp Material guideline. */
  .tab { padding: 9px 14px; }
  button { padding: 11px 16px; }
  button.primary { padding: 12px 20px; }
  input[type="file"]::file-selector-button { padding: 10px 14px; }
  input[type="color"] { width: 44px; height: 32px; }
  input[type="range"] { height: 32px; }
}