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

:root {
  --panel-w: 300px;
  --bg: #101014;
  --panel-bg: #18181c;
  --panel-header: #1e1e24;
  --surface: #24242a;
  --surface-hover: #2a2a32;
  --border: #2e2e36;
  --text: #d8d8e0;
  --text-dim: #707080;
  --text-muted: #50505c;
  --accent: #6c8cff;
  --accent-dim: rgba(108, 140, 255, 0.12);
  --accent-glow: rgba(108, 140, 255, 0.25);
  --danger: #ff6b6b;
  --radius: 8px;
  --radius-sm: 6px;
}

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

/* ─── Layout ─────────────────────────────────────── */
#app {
  display: flex;
  height: 100%;
}

#viewport-wrap {
  flex: 1;
  position: relative;
  overflow: hidden;
}

#viewport {
  display: block;
  width: 100%;
  height: 100%;
}

#viewport-hint {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--text-muted);
  font-size: 14px;
  letter-spacing: 0.3px;
  pointer-events: none;
  opacity: 0.7;
  transition: opacity 0.4s;
}

#viewport-hint.hidden {
  opacity: 0;
}

#light-indicator {
  position: absolute;
  top: 16px;
  left: 16px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background: radial-gradient(circle at 40% 40%, #ffe8a0, #ff9800 80%);
  box-shadow: 0 0 12px rgba(255, 160, 0, 0.4);
  opacity: 0.6;
  pointer-events: none;
  transition: transform 0.1s linear;
}

/* ─── Panel ──────────────────────────────────────── */
#panel {
  width: var(--panel-w);
  min-width: var(--panel-w);
  background: var(--panel-bg);
  border-left: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  user-select: none;
}

#panel-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 16px;
  background: var(--panel-header);
  border-bottom: 1px solid var(--border);
}

#panel-header h1 {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.3px;
}

#panel-scroll {
  flex: 1;
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

#panel-scroll::-webkit-scrollbar { width: 5px; }
#panel-scroll::-webkit-scrollbar-track { background: transparent; }
#panel-scroll::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

#panel-footer {
  padding: 12px 16px;
  border-top: 1px solid var(--border);
}

/* ─── Sections ───────────────────────────────────── */
.section {
  border-bottom: 1px solid var(--border);
}

.section-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  background: none;
  border: none;
  color: var(--text);
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  cursor: pointer;
  transition: background 0.15s;
}

.section-toggle:hover {
  background: var(--surface);
}

.toggle-icon {
  display: inline-block;
  width: 0;
  height: 0;
  border-left: 5px solid var(--text-dim);
  border-top: 4px solid transparent;
  border-bottom: 4px solid transparent;
  transition: transform 0.2s;
}

.section-toggle.open .toggle-icon {
  transform: rotate(90deg);
}

.section-body {
  padding: 0 16px 14px;
}

/* ─── Drop Zones ─────────────────────────────────── */
.texture-slots {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.drop-zone {
  position: relative;
  height: 72px;
  border: 1.5px dashed var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.2s;
  overflow: hidden;
}

.drop-zone:hover {
  border-color: var(--accent);
  background: var(--accent-dim);
}

.drop-zone.drag-over {
  border-color: var(--accent);
  background: var(--accent-dim);
  box-shadow: inset 0 0 20px var(--accent-dim);
}

.drop-zone.has-image {
  border-style: solid;
  border-color: var(--accent);
}

.drop-content {
  display: flex;
  align-items: center;
  gap: 10px;
  height: 100%;
  padding: 0 16px;
  color: var(--text-dim);
}

.drop-icon { opacity: 0.5; flex-shrink: 0; }
.drop-text { font-size: 12px; font-weight: 500; }

.drop-preview {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: none;
  border-radius: calc(var(--radius) - 2px);
}

.drop-zone.has-image .drop-preview { display: block; }
.drop-zone.has-image .drop-content { display: none; }

.drop-clear {
  position: absolute;
  top: 4px;
  right: 4px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  border: none;
  background: rgba(0,0,0,0.7);
  color: #fff;
  font-size: 14px;
  line-height: 1;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  transition: background 0.15s;
}

.drop-clear:hover { background: var(--danger); }
.drop-zone.has-image .drop-clear { display: flex; }

/* ─── Geometry Grid ──────────────────────────────── */
.geo-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 6px;
}

.geo-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 4px 8px;
  background: var(--surface);
  border: 1.5px solid transparent;
  border-radius: var(--radius);
  color: var(--text-dim);
  cursor: pointer;
  transition: all 0.15s;
}

.geo-btn span { font-size: 10px; font-weight: 500; }

.geo-btn:hover {
  background: var(--surface-hover);
  color: var(--text);
}

.geo-btn.active {
  border-color: var(--accent);
  background: var(--accent-dim);
  color: var(--accent);
}

/* ─── Controls ───────────────────────────────────── */
.control-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
}

.control-row label {
  font-size: 11px;
  color: var(--text-dim);
  min-width: 54px;
  font-weight: 500;
}

.control-inputs {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 8px;
}

.val {
  font-size: 11px;
  color: var(--text-muted);
  min-width: 28px;
  text-align: right;
  font-variant-numeric: tabular-nums;
  font-weight: 500;
}

/* Range inputs */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  flex: 1;
  height: 4px;
  background: var(--surface);
  border-radius: 2px;
  outline: none;
  cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  box-shadow: 0 0 0 1px var(--accent);
  cursor: pointer;
  transition: box-shadow 0.15s;
}

input[type="range"]::-webkit-slider-thumb:hover {
  box-shadow: 0 0 0 3px var(--accent-glow);
}

input[type="range"]::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  border: 2px solid var(--panel-bg);
  cursor: pointer;
}

/* Toggle switches */
.toggle-row {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 12px;
  color: var(--text-dim);
  cursor: pointer;
  margin-bottom: 8px;
  font-weight: 500;
}

.toggle-switch {
  position: relative;
  width: 32px;
  height: 18px;
  flex-shrink: 0;
}

.toggle-switch input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}

.toggle-track {
  position: absolute;
  inset: 0;
  background: var(--surface);
  border-radius: 9px;
  transition: background 0.2s;
}

.toggle-track::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 14px;
  height: 14px;
  background: var(--text-dim);
  border-radius: 50%;
  transition: all 0.2s;
}

.toggle-switch input:checked + .toggle-track {
  background: var(--accent);
}

.toggle-switch input:checked + .toggle-track::after {
  left: 16px;
  background: #fff;
}

/* Background buttons */
.bg-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 4px;
}

.bg-label {
  font-size: 11px;
  color: var(--text-dim);
  font-weight: 500;
  min-width: 54px;
}

.bg-btns {
  display: flex;
  gap: 6px;
}

.bg-btn {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  border: 2px solid var(--border);
  background: none;
  cursor: pointer;
  padding: 3px;
  transition: border-color 0.15s;
}

.bg-btn span {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: 3px;
}

.bg-btn:hover { border-color: var(--text-dim); }
.bg-btn.active { border-color: var(--accent); }

/* ─── Reset Button ───────────────────────────────── */
#reset-all {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 12px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s;
}

#reset-all:hover {
  background: rgba(255, 107, 107, 0.08);
  border-color: rgba(255, 107, 107, 0.3);
  color: var(--danger);
}

/* ─── Viewport drag state ────────────────────────── */
#viewport-wrap.dragging::after {
  content: 'Drop texture';
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(108, 140, 255, 0.08);
  border: 2px dashed var(--accent);
  color: var(--accent);
  font-size: 16px;
  font-weight: 500;
  letter-spacing: 0.5px;
  pointer-events: none;
  z-index: 10;
}

/* ─── Responsive ─────────────────────────────────── */
@media (max-width: 700px) {
  #app { flex-direction: column-reverse; }
  #panel {
    width: 100%;
    min-width: unset;
    max-height: 45vh;
    border-left: none;
    border-top: 1px solid var(--border);
  }
  #viewport-wrap { min-height: 55vh; }
}