/* ── Design Tokens ─────────────────────────────────────── */
:root {
  --bg-app:        #f0f0f0;
  --bg-panel:      #ffffff;
  --bg-section:    #f7f7f7;
  --bg-section-hov:#eef0f3;
  --border:        #e0e0e0;
  --border-focus:  #4f8ef7;
  --text:          #1a1a1a;
  --text-muted:    #777777;
  --accent:        #4f8ef7;
  --accent-hov:    #3a7de8;
  --danger:        #e05252;
  --paper-shadow:  0 4px 24px rgba(0,0,0,0.12), 0 1px 4px rgba(0,0,0,0.08);
  --radius:        6px;
  --radius-sm:     4px;
  --panel-w:       272px;
  --topbar-h:      44px;
  --transition:    0.15s ease;
}

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

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 13px;
  color: var(--text);
  background: var(--bg-app);
  overflow: hidden;
}

/* ── Screen switcher ───────────────────────────────────── */
.screen { display: none; }
.screen.active { display: flex; flex-direction: column; height: 100vh; }

/* ── Buttons ───────────────────────────────────────────── */
button {
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
  border: none;
  background: none;
}

/* ── Field rows (shared panel inputs) ─────────────────── */
.field-row {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 5px 0;
}

.field-label {
  flex: 1;
  color: var(--text-muted);
  font-size: 12px;
}

.field-input {
  width: 72px;
  padding: 4px 6px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-family: inherit;
  color: var(--text);
  background: var(--bg-panel);
  outline: none;
  transition: border-color var(--transition);
}
.field-input:focus { border-color: var(--border-focus); }

.field-color {
  width: 32px;
  height: 24px;
  padding: 1px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  background: none;
}

/* ── Unified slider design (covers all <input type="range">) ── */
input[type="range"],
.field-range {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  flex: 1;
  height: 6px;
  background: var(--border);
  border-radius: 999px;
  border: none;
  outline: none;
  cursor: pointer;
  accent-color: var(--accent);
  transition: background 0.1s ease;
}
input[type="range"]::-webkit-slider-runnable-track,
.field-range::-webkit-slider-runnable-track {
  height: 6px;
  background: transparent;
  border-radius: 999px;
}
input[type="range"]::-moz-range-track,
.field-range::-moz-range-track {
  height: 6px;
  background: var(--border);
  border-radius: 999px;
  border: none;
}
input[type="range"]::-webkit-slider-thumb,
.field-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -5px; /* center 16px thumb on 6px track */
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.1s ease;
}
input[type="range"]::-moz-range-thumb,
.field-range::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.1s ease;
}
input[type="range"]:hover::-webkit-slider-thumb,
.field-range:hover::-webkit-slider-thumb {
  transform: scale(1.15);
  box-shadow: 0 2px 6px rgba(0,0,0,0.25);
}
input[type="range"]:hover::-moz-range-thumb,
.field-range:hover::-moz-range-thumb {
  transform: scale(1.15);
  box-shadow: 0 2px 6px rgba(0,0,0,0.25);
}
input[type="range"]:focus-visible,
.field-range:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
input[type="range"]:disabled,
.field-range:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.field-range-val {
  font-size: 11px;
  color: var(--text-muted);
  min-width: 30px;
  text-align: right;
}

/* ── Toggle switch ─────────────────────────────────────── */
.toggle {
  position: relative;
  display: inline-flex;
  cursor: pointer;
}
.toggle input { opacity: 0; width: 0; height: 0; position: absolute; }
.toggle-track {
  width: 32px;
  height: 18px;
  border-radius: 9px;
  background: var(--border);
  transition: background var(--transition);
  position: relative;
}
.toggle-track::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
  transition: transform var(--transition);
}
.toggle input:checked + .toggle-track { background: var(--accent); }
.toggle input:checked + .toggle-track::after { transform: translateX(14px); }

/* ── Swatch palette ─────────────────────────────────────── */
.swatch-group {
  display: flex;
  flex-direction: column;
  gap: 5px;
}
.swatch-chip {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 5px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  background: var(--bg-panel);
  transition: border-color var(--transition), box-shadow var(--transition);
  user-select: none;
}
.swatch-chip:hover { border-color: #bbb; }
.swatch-chip.selected {
  border-color: var(--text);
  box-shadow: 0 0 0 2px rgba(0,0,0,0.15);
}
.swatch-box {
  width: 18px;
  height: 18px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(0,0,0,0.1);
  flex-shrink: 0;
}
.swatch-name {
  font-size: 12px;
  color: var(--text);
}
.swatch-box--gradient {
  width: 56px;
}

/* ── Section sub-header ─────────────────────────────────── */
.section-subheader {
  font-size: 10px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin: 10px 0 5px;
}

/* ── Control groups (sidebar grouping) ──────────────────── */
.ctrl-group {
  background: var(--bg-section);
  border-radius: var(--radius);
  padding: 10px 12px;
  margin-bottom: 10px;
}
.ctrl-group-label {
  font-size: 10px;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 8px;
}
.ctrl-btn-group {
  display: flex;
  gap: 4px;
  margin-bottom: 6px;
}
.ctrl-btn-group:last-child { margin-bottom: 0; }
.ctrl-btn {
  flex: 1;
  padding: 5px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--bg-panel);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  white-space: nowrap;
}
.ctrl-btn:hover { background: var(--bg-section-hov); color: var(--text); }
.ctrl-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
.ctrl-toggle-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}
.ctrl-toggle-row:last-child { margin-bottom: 0; }
.ctrl-toggle-label {
  font-size: 12px;
  color: var(--text);
}
.ctrl-slider-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}
.ctrl-slider-row:last-child { margin-bottom: 0; }
.ctrl-slider-label {
  flex: 1;
  font-size: 12px;
  color: var(--text-muted);
}
.ctrl-slider-val {
  font-size: 11px;
  color: var(--text-muted);
  min-width: 36px;
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* ── Textarea for poster text ────────────────────────────── */
.poster-textarea {
  width: 100%;
  min-height: 44px;
  resize: vertical;
  padding: 6px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 12px;
  font-family: inherit;
  color: var(--text);
  background: var(--bg-panel);
  outline: none;
  transition: border-color var(--transition);
  margin-bottom: 6px;
}
.poster-textarea:focus { border-color: var(--border-focus); }

/* ── Slider row (uses unified slider style above) ───────── */
.slider-row {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 4px 0;
}

/* ── Layout buttons ─────────────────────────────────────── */
.layout-btns {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-bottom: 10px;
}
.layout-btn {
  padding: 4px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 11px;
  font-weight: 500;
  color: var(--text-muted);
  background: var(--bg-panel);
  cursor: pointer;
  transition: background var(--transition), color var(--transition), border-color var(--transition);
  white-space: nowrap;
}
.layout-btn:hover { background: var(--bg-section-hov); color: var(--text); }
.layout-btn.active {
  background: var(--text);
  border-color: var(--text);
  color: #fff;
}

/* ── Background image row ───────────────────────────────── */
.bg-image-row {
  display: flex;
  gap: 6px;
  margin-top: 8px;
}

/* ── Letter library grid ────────────────────────────────── */
.letter-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 4px;
  margin-bottom: 10px;
}
.letter-btn {
  padding: 10px 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 18px;
  font-family: 'QSci', sans-serif;
  font-weight: 400;
  color: var(--text);
  background: var(--bg-panel);
  cursor: pointer;
  text-align: center;
  transition: background var(--transition), border-color var(--transition), color var(--transition);
}
.letter-btn:hover {
  background: var(--bg-section-hov);
  border-color: var(--accent);
  color: var(--accent);
}

/* ── Overlay controls ───────────────────────────────────── */
.overlay-controls {
  margin-top: 4px;
  padding-top: 10px;
  border-top: 1px solid var(--border);
}
.overlay-hdr {
  font-size: 12px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
}
.overlay-hint {
  font-size: 11px;
  color: var(--text-muted);
  padding: 4px 0;
}
.overlay-del-btn {
  width: 100%;
  margin-top: 8px;
  padding: 6px 10px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--danger);
  background: transparent;
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);
  text-align: center;
}
.overlay-del-btn:hover { background: var(--bg-section-hov); border-color: var(--danger); }

/* ── Position grid ──────────────────────────────────────── */
.pos-element-section {
  margin-bottom: 14px;
}
.pos-element-label {
  font-weight: 600;
  margin-bottom: 5px;
}
.pos-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 4px;
}
.pos-btn {
  padding: 8px 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 16px;
  color: var(--text-muted);
  background: var(--bg-panel);
  cursor: pointer;
  text-align: center;
  transition: background var(--transition), border-color var(--transition), color var(--transition);
}
.pos-btn:hover { background: var(--bg-section-hov); color: var(--text); }
.pos-btn.active {
  background: var(--text);
  border-color: var(--text);
  color: #fff;
}

/* ── Loading overlay ─────────────────────────────────────── */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: var(--bg-app);
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
}
.loading-inner {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 13px;
  color: var(--text-muted);
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-spinner {
  width: 18px;
  height: 18px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}