:root[data-theme="dark"] {
  --bg: #0c0c0c;
  --panel: #121212;
  --panel-2: #1a1a1a;
  --border: #262626;
  --text: #f5f5f5;
  --text-muted: #8c8c8c;
  --accent: #ffffff;
  --accent-fg: #000000;
  --layer-boundary: #3b82f6;
  --layer-column: #10b981;
  --layer-obstacle: #ef4444;
  --layer-default: #a3a3a3;
}
:root[data-theme="light"] {
  --bg: #f5f5f5;
  --panel: #ffffff;
  --panel-2: #fafafa;
  --border: #e5e5e5;
  --text: #171717;
  --text-muted: #737373;
  --accent: #000000;
  --accent-fg: #ffffff;
  --layer-boundary: #2563eb;
  --layer-column: #059669;
  --layer-obstacle: #dc2626;
  --layer-default: #737373;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { height: 100vh; overflow: hidden; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; background: var(--bg); color: var(--text); }

#app { display: flex; flex-direction: column; height: 100vh; }

#topbar {
  height: 56px; display: flex; align-items: center; gap: 16px;
  background: var(--panel); border-bottom: 1px solid var(--border); padding: 0 20px;
  position: relative; z-index: 100;
}
.brand { font-weight: 700; font-size: 15px; letter-spacing: 0.05em; text-transform: uppercase; }
.brand span { color: var(--text-muted); font-weight: 400; }
.spacer { flex: 1; }

.btn {
  border: 1px solid var(--border); background: var(--panel-2); color: var(--text);
  padding: 8px 16px; border-radius: 4px; cursor: pointer; font-size: 13px;
  font-weight: 500; display: inline-flex; align-items: center; gap: 6px;
  transition: all 0.15s ease;
}
.btn:hover:not(:disabled) { border-color: var(--accent); background: var(--panel); }
.btn:disabled { opacity: 0.3; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }
.btn-primary:hover:not(:disabled) { background: var(--panel-2); color: var(--text); border-color: var(--accent); }
.btn-ghost { background: transparent; border-color: transparent; }
.btn-ghost:hover:not(:disabled) { background: var(--panel-2); }
.btn.toggleable.active { background: var(--layer-boundary); color: #fff; border-color: var(--layer-boundary); }

.menu {
  position: absolute; top: 52px; right: 80px; background: var(--panel);
  border: 1px solid var(--border); border-radius: 4px; display: flex; flex-direction: column;
  overflow: hidden; z-index: 1000; box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}
.menu button { padding: 10px 20px; background: none; border: none; color: var(--text); text-align: left; cursor: pointer; font-size: 12px; }
.menu button:hover { background: var(--panel-2); }
.hidden { display: none !important; }

main { flex: 1; display: flex; overflow: hidden; position: relative; }

/* Drag and Drop Zone Fullscreen Overlay prior to upload */
#upload-overlay {
  position: absolute; inset: 0; background: var(--bg); z-index: 50;
  display: flex; flex-direction: column; align-items: center; justify-content: center; padding: 20px;
}
#dropzone {
  border: 2px dashed var(--border); border-radius: 8px; max-width: 500px; width: 100%;
  padding: 60px 40px; text-align: center; transition: all 0.2s ease; background: var(--panel);
}
#dropzone.dragover { border-color: var(--accent); background: var(--panel-2); }

#viewport { flex: 1; position: relative; background: var(--bg); overflow: hidden; }
#three-canvas { display: block; width: 100%; height: 100%; }

/* Right Inspector Panel Only */
#right-panel {
  width: 380px; background: var(--panel); border-left: 1px solid var(--border);
  display: flex; flex-direction: column; flex-shrink: 0; z-index: 10; overflow: hidden;
}
.panel-scroll-content { flex: 1; overflow-y: auto; padding: 20px; display: flex; flex-direction: column; gap: 24px; }

h3 { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.1em; color: var(--text-muted); margin-bottom: 12px; display: flex; justify-content: space-between; align-items: center; }
.panel-section { border-bottom: 1px solid var(--border); padding-bottom: 20px; }
.panel-section:last-of-type { border-bottom: none; }

/* Custom Checkbox Design */
.layer-item {
  display: flex; align-items: center; gap: 10px; padding: 8px 10px;
  background: var(--panel-2); border: 1px solid var(--border); border-radius: 4px;
  margin-bottom: 6px; cursor: pointer; font-size: 13px; transition: all 0.15s ease;
}
.layer-item:hover { border-color: var(--text-muted); }
.layer-item.selected { border-color: var(--accent); background: var(--panel); }
.layer-item .dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; flex-shrink: 0; }
.layer-item .layer-name { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.layer-item .count { font-size: 11px; color: var(--text-muted); font-family: monospace; }

.layer-item input[type="checkbox"] {
  appearance: none; width: 14px; height: 14px; border: 1px solid var(--border);
  border-radius: 3px; background: var(--panel-2); cursor: pointer; display: flex;
  align-items: center; justify-content: center; transition: all 0.1s;
}
.layer-item input[type="checkbox"]:checked {
  background: var(--accent); border-color: var(--accent);
}
.layer-item input[type="checkbox"]:checked::after {
  content: "✓"; font-size: 10px; color: var(--accent-fg); font-weight: bold;
}

/* Custom Target Assign Selection Grid */
.assign-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 6px; margin-top: 10px; }
.assign-btn {
  padding: 8px; font-size: 12px; font-weight: 600; text-align: center; border-radius: 4px;
  cursor: pointer; border: 1px solid var(--border); transition: all 0.15s ease; background: var(--panel-2);
}
.assign-btn:hover { border-color: var(--accent); }

/* Selection Inspector Area */
.selection-list { max-height: 200px; overflow-y: auto; border: 1px solid var(--border); border-radius: 4px; }
.selection-item {
  display: flex; align-items: center; justify-content: space-between;
  padding: 6px 10px; font-size: 12px; border-bottom: 1px solid var(--border);
}
.selection-item:last-child { border-bottom: none; }
.selection-item .meta-desc { font-family: monospace; color: var(--text-muted); }
.selection-item .btn-remove { background: none; border: none; color: var(--text-muted); cursor: pointer; font-size: 12px; }
.selection-item .btn-remove:hover { color: var(--text); }

/* HUD / Tools overlays */
#hud {
  position: absolute; bottom: 16px; left: 16px; display: flex; flex-direction: column; gap: 4px;
  font-size: 11px; font-family: monospace; color: var(--text-muted); pointer-events: none;
  background: rgba(0,0,0,0.8); padding: 8px 12px; border-radius: 4px; border: 1px solid #222;
}
:root[data-theme="light"] #hud { background: rgba(255,255,255,0.9); border-color: var(--border); color: var(--text); }
#viewport-tools { position: absolute; top: 16px; left: 16px; display: flex; gap: 6px; }
#viewport-tools button {
  width: 36px; height: 36px; border-radius: 4px; border: 1px solid var(--border);
  background: var(--panel); color: var(--text); cursor: pointer; display: flex; align-items: center; justify-content: center;
}
#viewport-tools button.active { background: var(--accent); color: var(--accent-fg); }

/* Progress bar inside drag zone */
.bar { height: 6px; background: var(--border); border-radius: 3px; overflow: hidden; margin: 12px 0; width: 100%; }
.bar-fill { height: 100%; width: 0%; background: var(--accent); transition: width 0.15s ease; }

#loading-overlay {
  position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 12px; background: rgba(0,0,0,0.7); backdrop-filter: blur(4px); z-index: 200;
}

#hover-tooltip {
  position: fixed; z-index: 1500; pointer-events: none; background: rgba(0, 0, 0, 0.9);
  border: 1px solid #333; color: #fff; font-size: 11px; padding: 4px 8px; border-radius: 4px;
  white-space: nowrap; font-family: monospace; box-shadow: 0 4px 12px rgba(0,0,0,0.5);
}
:root[data-theme="light"] #hover-tooltip { background: #fff; border-color: var(--border); color: #000; box-shadow: 0 4px 12px rgba(0,0,0,0.15); }

#toast-container { position: fixed; bottom: 20px; right: 400px; display: flex; flex-direction: column; gap: 8px; z-index: 1100; }
.toast {
  background: var(--panel); border: 1px solid var(--border); padding: 12px 18px; border-radius: 4px;
  font-size: 13px; font-weight: 500; box-shadow: 0 4px 14px rgba(0,0,0,0.3); color: var(--text);
  animation: slideIn 0.2s cubic-bezier(0, 0, 0.2, 1);
}
@keyframes slideIn { from { transform: translateY(10px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

#hud-mouse {
  position: absolute; bottom: 10px; right: 12px; font-size: 11px; color: var(--text-muted);
  background: rgba(0,0,0,.3); padding: 4px 8px; border-radius: 4px; font-family: monospace;
}
:root[data-theme="light"] #hud-mouse {background: rgba(255,255,255,.6);}