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

:root {
  --bg:        #0e0e10;
  --bg-2:      #18181c;
  --bg-3:      #222228;
  --border:    rgba(255,255,255,.08);
  --border-2:  rgba(255,255,255,.14);
  --text:      #f0f0f2;
  --text-2:    #9090a0;
  --text-3:    #5a5a6a;
  --accent:    #7c6af7;
  --accent-h:  #6557e0;
  --radius:    12px;
  --radius-sm: 8px;
  font-size: 15px;
}

html { background: var(--bg); color: var(--text); font-family: system-ui, -apple-system, sans-serif; min-height: 100vh; }
body { min-height: 100vh; }

/* ── Layout ───────────────────────────────────────────── */
.app  { max-width: 900px; margin: 0 auto; padding: 2.5rem 1.25rem 4rem; }

/* ── Header ───────────────────────────────────────────── */
.header      { margin-bottom: 2rem; }
.header h1   { font-size: 1.6rem; font-weight: 600; letter-spacing: -.02em; }
.header .subtitle { font-size: .875rem; color: var(--text-2); margin-top: .3rem; }

/* ── Drop zone ────────────────────────────────────────── */
.drop-zone {
  border: 1.5px dashed var(--border-2);
  border-radius: var(--radius);
  padding: 2.75rem 1.5rem;
  text-align: center;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  transition: background .2s, border-color .2s;
  background: var(--bg-2);
}
.drop-zone:hover, .drop-zone.drag { background: var(--bg-3); border-color: var(--accent); }
.drop-icon   { width: 36px; height: 36px; opacity: .35; }
.drop-label  { font-size: .9rem; color: var(--text-2); }
.drop-sub    { font-size: .78rem; color: var(--text-3); }

/* ── Panel ────────────────────────────────────────────── */
.panel {
  margin-top: 1rem;
  background: var(--bg-2);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .9rem 1rem;
}
.panel-title {
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--text-3);
  margin-bottom: .75rem;
}
.panel-title-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0;
}
.panel-title-row .panel-title { margin-bottom: 0; }

/* ── Controls grid ────────────────────────────────────── */
.controls {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-top: .5rem;
}
@media (max-width: 520px) { .controls { grid-template-columns: 1fr; } }

.ctrl {
  background: var(--bg-3);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .75rem .9rem;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.ctrl label {
  font-size: .72rem;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--text-3);
}
.ctrl-row { display: flex; align-items: center; gap: 10px; }
.ctrl-row input[type="range"] { flex: 1; accent-color: var(--accent); cursor: pointer; }
.ctrl-row input[type="number"] {
  flex: 1;
  background: var(--bg-2);
  border: .5px solid var(--border-2);
  border-radius: 6px;
  color: var(--text);
  padding: .35rem .6rem;
  font-size: .9rem;
  outline: none;
}
.ctrl-row input[type="number"]:focus { border-color: var(--accent); }
.val { font-size: .9rem; font-weight: 500; min-width: 46px; text-align: right; color: var(--text); }
.gap-sm { gap: 8px; }
.hint-inline { font-size: .78rem; color: var(--text-3); }

/* ── Toggle switch ────────────────────────────────────── */
.toggle-label {
  display: flex; align-items: center; gap: 8px; cursor: pointer; user-select: none;
}
.toggle-label input[type="checkbox"] { display: none; }
.toggle-track {
  width: 36px; height: 20px;
  background: var(--bg-3);
  border: .5px solid var(--border-2);
  border-radius: 10px;
  position: relative;
  transition: background .2s;
  flex-shrink: 0;
}
.toggle-thumb {
  position: absolute; top: 3px; left: 3px;
  width: 14px; height: 14px;
  background: var(--text-3); border-radius: 50%;
  transition: left .2s, background .2s;
}
.toggle-label input:checked ~ .toggle-track { background: var(--accent); border-color: var(--accent); }
.toggle-label input:checked ~ .toggle-track .toggle-thumb { left: 19px; background: #fff; }

/* ── Segmented buttons ────────────────────────────────── */
.btn-group { display: flex; gap: 6px; flex-wrap: wrap; }
.seg-btn {
  display: flex; align-items: center; gap: 5px;
  background: var(--bg-2);
  border: .5px solid var(--border);
  border-radius: 6px;
  padding: .28rem .65rem;
  font-size: .78rem;
  color: var(--text-2);
  cursor: pointer;
  transition: background .15s, border-color .15s, color .15s;
  white-space: nowrap;
}
.seg-btn svg { flex-shrink: 0; opacity: .7; }
.seg-btn:hover { background: var(--bg); color: var(--text); }
.seg-btn.active { background: var(--bg); border-color: var(--accent); color: var(--text); }
.seg-btn.active svg { opacity: 1; }

/* ── Color picker ─────────────────────────────────────── */
.color-pick {
  width: 32px; height: 32px;
  border: .5px solid var(--border-2); border-radius: 6px;
  background: none; cursor: pointer; padding: 2px; flex-shrink: 0;
}

/* ── Grid params (collapsible) ────────────────────────── */
.grid-params { margin-top: .75rem; }

/* ── Legend preview ───────────────────────────────────── */
.legend-preview-wrap {
  background: var(--bg-3);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .85rem;
  margin-top: .25rem;
  overflow-x: auto;
}

/* ── Hint ─────────────────────────────────────────────── */
.hint {
  font-size: .8rem;
  color: var(--text-3);
  line-height: 1.5;
  margin-top: .75rem;
  padding: .5rem .75rem;
  border-left: 2px solid var(--border-2);
}

/* ── Previews ─────────────────────────────────────────── */
.previews {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 1rem;
}
@media (max-width: 520px) { .previews { grid-template-columns: 1fr; } }

.preview-box {
  background: var(--bg-2);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .85rem;
  display: flex; flex-direction: column; gap: 8px;
  min-height: 160px;
}
.preview-title { font-size: .72rem; text-transform: uppercase; letter-spacing: .06em; color: var(--text-3); }
.preview-box canvas, #svg-container svg {
  width: 100%; height: auto; max-height: 260px; object-fit: contain; display: block; border-radius: 4px;
}
#svg-container { overflow: hidden; }

/* ── Buttons ──────────────────────────────────────────── */
.btn-row { display: flex; align-items: center; gap: 10px; margin-top: 1.25rem; flex-wrap: wrap; }
.btn {
  background: var(--bg-2);
  border: .5px solid var(--border-2);
  border-radius: var(--radius-sm);
  padding: .55rem 1.2rem;
  font-size: .875rem; color: var(--text);
  cursor: pointer; transition: background .15s, transform .1s;
}
.btn:hover:not(:disabled)  { background: var(--bg-3); }
.btn:active:not(:disabled) { transform: scale(.98); }
.btn:disabled              { opacity: .4; cursor: not-allowed; }
.btn-primary { background: var(--accent); border-color: transparent; color: #fff; font-weight: 500; }
.btn-primary:hover:not(:disabled) { background: var(--accent-h); }

/* ── Palette tune editor ──────────────────────────────── */
#palette-tune-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: .25rem;
}
.pt-tile {
  width: 44px;
  height: 44px;
  border-radius: 6px;
  border: 2px solid transparent;
  cursor: pointer;
  position: relative;
  transition: transform .1s, border-color .15s;
  flex-shrink: 0;
}
.pt-tile:hover { transform: scale(1.08); }
.pt-tile .pt-num {
  position: absolute;
  bottom: 2px; right: 3px;
  font-size: 9px;
  font-family: monospace;
  font-weight: bold;
  line-height: 1;
  pointer-events: none;
}
.pt-tile.selected {
  border-color: var(--accent) !important;
  transform: scale(1.1);
  z-index: 2;
}
.pt-tile.in-range {
  border-color: rgba(124,106,247,.5) !important;
  opacity: .85;
}
.pt-tile.merged {
  border-color: #e86 !important;
  opacity: .7;
}
.pt-tile.expanded {
  border-color: #4c9 !important;
}
/* stripe overlay for merged tiles */
.pt-tile.merged::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 4px;
  background: repeating-linear-gradient(
    45deg,
    rgba(0,0,0,.18) 0px, rgba(0,0,0,.18) 3px,
    transparent 3px, transparent 7px
  );
  pointer-events: none;
}

.range-actions {
  margin-top: .85rem;
  background: var(--bg-3);
  border: .5px solid var(--border-2);
  border-radius: var(--radius-sm);
  padding: .75rem 1rem;
}
.range-info {
  font-size: .82rem;
  color: var(--text-2);
}

/* ── Download groups ──────────────────────────────────── */
.download-group {
  margin-top: .85rem;
  background: var(--bg-2);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .75rem 1rem;
}
.dl-group-label {
  font-size: .72rem;
  text-transform: uppercase;
  letter-spacing: .07em;
  color: var(--text-3);
  margin-bottom: .5rem;
}
.download-group .btn-row { margin-top: 0; }

/* ── Utilities ────────────────────────────────────────── */
.hidden { display: none !important; }
.status { font-size: .82rem; color: var(--text-2); }
.info-box {
  margin-top: 1rem;
  background: var(--bg-2);
  border: .5px solid var(--border);
  border-radius: var(--radius-sm);
  padding: .7rem 1rem;
  font-size: .82rem; color: var(--text-2); line-height: 1.6;
}