:root {
  --bg-color: #ffffff;
  --text-color: #0f172a;
  --text-light: #64748b;
  --accent-color: #3b82f6;
  --bullet-color: #cbd5e1;
  --bullet-hover: #3b82f6;
  --border-color: #e2e8f0;
  --focus-ring: rgba(59, 130, 246, 0.2);
  --btn-hover: #f1f5f9;
}

[data-theme="dark"] {
  --bg-color: #0a1128;
  --text-color: #f8fafc;
  --text-light: #94a3b8;
  --accent-color: #60a5fa;
  --bullet-color: #475569;
  --bullet-hover: #60a5fa;
  --border-color: #1e2a4a;
  --focus-ring: rgba(96, 165, 250, 0.2);
  --btn-hover: #162445;
}

* { box-sizing: border-box; }

body {
  margin: 0; padding: 0;
  font-family: 'Inter', -apple-system, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-color);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Clear all bounds, workspace spans seamlessly */
#app {
  width: 100%;
  max-width: 800px;
  margin: 40px 20px;
  padding: 0;
  background: transparent;
  border-radius: 0;
  box-shadow: none;
  border: none;
}

header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.search-box {
  flex-grow: 1;
  margin: 0 20px;
  max-width: 300px;
}

.search-input {
  width: 100%;
  padding: 8px 16px;
  border-radius: 20px;
  border: 1px solid var(--border-color);
  background: transparent;
  color: var(--text-color);
  font-family: inherit;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.search-input:focus {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px var(--focus-ring);
}

h1 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 0;
  letter-spacing: -0.02em;
  min-width: 150px;
}

.controls {
  display: flex;
  gap: 8px;
}

.controls button {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-color);
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s;
  padding: 0;
}

.controls button:hover {
  background: var(--btn-hover);
}

.controls button svg {
  width: 18px;
  height: 18px;
  fill: currentColor;
}

.tree-node .node-main {
  display: flex;
  align-items: flex-start;
  margin-bottom: 4px;
  position: relative;
  transition: opacity 0.2s;
}

.expand-toggle {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-light);
  user-select: none;
  transition: transform 0.2s ease, color 0.2s ease;
  font-size: 10px;
  margin-top: 2px;
}

.expand-toggle:hover { color: var(--text-color); }
.expand-toggle.collapsed { transform: rotate(-90deg); }
.expand-toggle.invisible { opacity: 0; pointer-events: none; }

.drag-handle {
  position: absolute;
  left: -10px;
  top: 2px;
  width: 14px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-light);
  opacity: 0;
  cursor: grab;
  transition: opacity 0.2s, color 0.2s;
}

.tree-node .node-main:hover .drag-handle {
  opacity: 0.4;
}

.drag-handle:hover {
  opacity: 1 !important;
  color: var(--text-color);
}

.drag-handle:active {
  cursor: grabbing;
}

.node-main.drag-over-top::before {
  content: '';
  position: absolute;
  top: -1px;
  left: 36px;
  right: 0;
  height: 2px;
  background: var(--accent-color);
  z-index: 10;
}

.node-main.drag-over-bottom::after {
  content: '';
  position: absolute;
  bottom: -1px;
  left: 36px;
  right: 0;
  height: 2px;
  background: var(--accent-color);
  z-index: 10;
}

.bullet {
  width: 6px;
  height: 6px;
  background-color: var(--bullet-color);
  border-radius: 50%;
  margin-top: 11px;
  margin-right: 12px;
  flex-shrink: 0;
  cursor: pointer;
  transition: all 0.2s ease;
  box-shadow: 0 0 0 4px transparent;
}

.bullet:hover {
  background-color: var(--bullet-hover);
  box-shadow: 0 0 0 6px var(--focus-ring);
  transform: scale(1.2);
}

.content {
  min-height: 1.6em;
  outline: none;
  font-size: 1rem;
  padding: 1px 4px;
  border-radius: 4px;
  transition: background-color 0.2s;
  word-break: break-word;
}

.content:focus { background-color: rgba(100, 116, 139, 0.05); }
.content[data-completed="true"] { text-decoration: line-through; opacity: 0.5; }

.text-container {
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}

.note-content {
  font-size: 0.85em;
  color: var(--text-light);
  min-height: 1.2em;
  outline: none;
  padding: 2px 4px;
  border-radius: 4px;
  margin-top: 2px;
  line-height: 1.4;
}

.note-content:empty:before {
  content: attr(placeholder);
  color: var(--text-light);
  opacity: 0.5;
  pointer-events: none;
  display: block;
}

.note-content:focus { background-color: rgba(100, 116, 139, 0.05); }

.breadcrumbs {
  display: flex;
  align-items: center;
  margin-bottom: 24px;
  font-size: 0.95rem;
  color: var(--text-light);
  padding: 8px 12px;
  background: var(--btn-hover);
  border-radius: 8px;
}

.breadcrumbs span {
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
  transition: background 0.2s, color 0.2s;
}

.breadcrumbs span:hover { background: var(--border-color); color: var(--text-color); }
.breadcrumbs .separator { margin: 0 4px; cursor: default; }
.breadcrumbs .separator:hover { background: transparent; color: var(--text-light); }

.children {
  margin-left: 24px;
  padding-left: 12px;
  border-left: 1px solid var(--border-color);
}