.tree-main {
  max-width: none;
  width: min(100% - 2rem, 72rem);
  margin: 0 auto;
  padding: 5rem 0 4rem;
}

.tree-header {
  width: min(100%, 68rem);
  margin-inline: auto;
}

.lesson-card,
.control-panel,
.board-card,
.side-panel {
  background: var(--wa-white);
  border: 1px solid var(--wa-gray-light);
  border-radius: 8px;
}

.lesson-card {
  display: grid;
  grid-template-columns: minmax(0, 28rem) minmax(0, 1fr);
  gap: 1rem;
  align-items: center;
  padding: 1.25rem;
  margin-bottom: 1rem;
}

.lesson-kicker,
.lesson-card h2,
.lesson-card p {
  margin: 0;
}

.lesson-kicker {
  color: var(--wa-orange-dark);
  font-weight: 700;
  font-size: 0.85rem;
}

.lesson-card h2 {
  font-size: clamp(1.2rem, 2vw, 1.45rem);
  line-height: 1.35;
}

.lesson-card > p {
  color: var(--wa-ink-light);
}

.lesson-copy {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 0.75rem;
  color: var(--wa-ink-light);
}

.lesson-copy p {
  margin: 0;
}

.control-panel {
  padding: 1rem;
  margin-bottom: 1rem;
}

.control-grid {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: 0.85rem;
  align-items: start;
}

.control-grid > .field {
  grid-column: span 3;
}

.field {
  display: grid;
  gap: 0.35rem;
}

.field-label {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  color: var(--wa-ink-light);
  font-size: 0.85rem;
  font-weight: 700;
}

.info-button {
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 999px;
  background: var(--wa-orange-pale);
  color: var(--wa-orange-dark);
  font: inherit;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
}

.info-button:hover {
  border-color: var(--wa-orange);
  background: var(--wa-white);
}

.field select,
.field input[type="range"],
.field input[type="text"] {
  width: 100%;
}

.field select,
.field input[type="text"] {
  min-height: 2.55rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 6px;
  background: var(--wa-white);
  color: var(--wa-ink);
  font: inherit;
  padding: 0.45rem 0.65rem;
}

.field-wide {
  grid-column: span 6;
}

.field-expression-input {
  grid-column: span 9;
}

.expression-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 0.1rem;
}

.tool-button {
  min-width: 2.4rem;
  min-height: 2.4rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 6px;
  background: var(--wa-white);
  color: var(--wa-ink);
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.control-panel.is-expression-custom .field-expression-input {
  grid-column: 1 / -1;
}

.control-panel.is-expression-custom .field-expression-input input {
  max-width: 34rem;
}

.tool-button:hover {
  border-color: var(--wa-orange);
  background: var(--wa-orange-pale);
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1rem;
  justify-content: flex-start;
}

.action-row .btn-primary {
  margin: 0;
}

.action-row > button {
  min-width: 6.4rem;
}

.action-button {
  border: 1px solid var(--wa-gray-light);
  border-radius: 6px;
  background: var(--wa-white);
  color: var(--wa-ink);
  font: inherit;
  font-weight: 700;
  padding: 0.65rem 1rem;
  cursor: pointer;
}

.action-button:hover {
  border-color: var(--wa-orange);
}

.action-button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.lab-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
}

.board-card {
  padding: 1rem;
  min-width: 0;
}

.board-heading {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.board-heading h2,
.board-heading p {
  margin: 0;
}

.board-heading h2 {
  font-size: 1.2rem;
}

.board-heading p {
  color: var(--wa-ink-light);
  font-size: 0.92rem;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 0.5rem;
  color: var(--wa-gray);
  font-size: 0.78rem;
}

.legend span {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  white-space: nowrap;
}

.swatch {
  width: 0.7rem;
  height: 0.7rem;
  border-radius: 999px;
  border: 1px solid var(--wa-gray-light);
  background: var(--wa-white);
}

.swatch.is-current {
  background: var(--wa-orange);
}

.swatch.is-visited {
  background: var(--wa-sea-light);
}

.swatch.is-next {
  background: var(--wa-orange-light);
}

.swatch.is-path {
  background: #ffe08a;
}

.tree-board {
  position: relative;
  min-height: 32rem;
  overflow: hidden;
  border: 1px solid var(--wa-gray-light);
  border-radius: 8px;
  background: var(--wa-white);
}

.tree-board.is-trie {
  min-height: 26rem;
  overflow: auto;
}

.tree-board.is-bplus {
  min-height: 30rem;
}

.tree-canvas {
  position: relative;
  min-width: 80rem;
  min-height: 24rem;
}

.tree-board.is-trie .tree-node {
  width: 3rem;
  height: 3rem;
  font-size: 0.68rem;
}

.tree-board.is-trie .tree-edge-label {
  font-size: 0.78rem;
}

.tree-edges {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.leaf-links {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.tree-edge {
  stroke: rgba(74, 124, 89, 0.36);
  stroke-width: 1.35;
}

.tree-edge.is-path {
  stroke: #d6a328;
}

.leaf-link {
  stroke: rgba(184, 92, 122, 0.62);
  stroke-dasharray: 2.2 2.2;
  stroke-linecap: round;
  stroke-width: 1.2;
}

.tree-edge-label {
  position: absolute;
  left: calc(var(--x) * 1%);
  top: calc(var(--y) * 1%);
  z-index: 1;
  display: grid;
  place-items: center;
  min-width: 1.35rem;
  height: 1.35rem;
  border: 1px solid rgba(255, 153, 0, 0.2);
  border-radius: 999px;
  background: var(--wa-white);
  color: var(--wa-orange-dark);
  font-size: 0.78rem;
  font-weight: 700;
  line-height: 1;
  transform: translate(-50%, -50%);
  pointer-events: none;
}

.tree-edge-label.is-path {
  border-color: rgba(214, 163, 40, 0.42);
  background: #fff4c2;
  color: var(--wa-ink);
}

.tree-node {
  position: absolute;
  left: calc(var(--x) * 1%);
  top: calc(var(--y) * 1%);
  display: grid;
  place-items: center;
  width: 4.3rem;
  height: 4.3rem;
  border: 2px solid rgba(204, 122, 0, 0.28);
  border-radius: 999px;
  background: var(--wa-white);
  color: var(--wa-ink);
  font-size: 0.72rem;
  font-weight: 700;
  line-height: 1.25;
  text-align: center;
  transform: translate(-50%, -50%) translate(var(--move-x, 0), var(--move-y, 0));
  transition: background 160ms ease, color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
  z-index: 1;
}

.tree-node.is-moving {
  transition: transform 520ms cubic-bezier(0.2, 0.8, 0.2, 1), background 160ms ease, color 160ms ease, box-shadow 160ms ease;
}

.tree-node > span:first-child {
  display: block;
}

.node-meta {
  display: block;
  margin-top: 0.08rem;
  font-size: 0.5rem;
  line-height: 1.1;
  opacity: 0.78;
}

.tree-node.is-root {
  border-color: rgba(74, 124, 89, 0.42);
}

.tree-node.is-target {
  border-color: #b85c7a;
  box-shadow: 0 0 0 2px rgba(184, 92, 122, 0.18);
}

.tree-node.is-next {
  background: var(--wa-orange-light);
}

.tree-node.is-visited {
  background: var(--wa-sea-light);
  color: var(--wa-sea);
}

.tree-node.is-current {
  background: var(--wa-orange);
  color: var(--wa-white);
  transform: translate(-50%, -50%) translate(var(--move-x, 0), var(--move-y, 0)) scale(1.04);
  box-shadow: 0 0 0 3px rgba(255, 153, 0, 0.24);
  z-index: 2;
}

.tree-node.is-path {
  background: #ffe08a;
  color: var(--wa-ink);
}

.tree-node.is-bplus-node {
  width: auto;
  min-width: 5.2rem;
  height: 3.7rem;
  padding: 0.45rem 0.75rem;
  border-radius: 8px;
  border-color: rgba(74, 124, 89, 0.34);
  font-size: 0.8rem;
}

.tree-node.is-bplus-node.is-leaf {
  border-color: rgba(184, 92, 122, 0.34);
  background: #fff9f2;
}

.node-kind {
  display: block;
  margin-top: 0.12rem;
  color: var(--wa-gray);
  font-size: 0.52rem;
  line-height: 1;
  text-transform: uppercase;
}

.node-badge {
  position: absolute;
  right: -0.25rem;
  bottom: -0.15rem;
  min-width: 1.35rem;
  height: 1.35rem;
  display: grid;
  place-items: center;
  border-radius: 999px;
  background: var(--wa-ink);
  color: var(--wa-white);
  font-size: 0.7rem;
}

.side-panel {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.75rem;
  padding: 1rem;
}

.status-card {
  border-right: 1px solid var(--wa-gray-light);
  padding-right: 0.75rem;
}

.status-card:last-child {
  border-right: 0;
  padding-right: 0;
}

.status-label,
.status-value {
  margin: 0;
}

.status-label {
  color: var(--wa-gray);
  font-size: 0.82rem;
  font-weight: 700;
}

.status-value {
  font-size: 1.35rem;
  font-weight: 700;
  line-height: 1.4;
}

.status-value.compact {
  font-size: 0.95rem;
  word-break: break-word;
}

.visit-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0.5rem 0 0;
  padding: 0;
  list-style: none;
}

.visit-list li {
  border: 1px solid var(--wa-gray-light);
  border-radius: 999px;
  background: var(--wa-bg);
  padding: 0.2rem 0.55rem;
  font-size: 0.78rem;
  font-weight: 700;
}

.is-hidden-control {
  display: none;
}

.info-modal {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: grid;
  place-items: center;
  padding: 1rem;
}

.info-modal.hidden {
  display: none;
}

.info-modal-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(26, 26, 26, 0.42);
}

.info-modal-panel {
  position: relative;
  display: grid;
  grid-template-rows: auto minmax(0, 1fr);
  z-index: 1;
  width: min(100%, 54rem);
  max-height: min(88vh, 46rem);
  overflow: hidden;
  border: 1px solid var(--wa-gray-light);
  border-radius: 8px;
  background: var(--wa-white);
}

.info-modal-header {
  position: sticky;
  top: 0;
  z-index: 2;
  border-bottom: 1px solid var(--wa-gray-light);
  background: var(--wa-white);
  padding: 1.35rem 3.8rem 1rem 1.35rem;
}

.info-modal-close {
  position: absolute;
  top: 1rem;
  right: 1rem;
  display: grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 999px;
  background: var(--wa-white);
  color: var(--wa-ink);
  cursor: pointer;
}

.info-modal-kicker {
  margin: 0 0 0.35rem;
  color: var(--wa-orange-dark);
  font-size: 0.78rem;
  font-weight: 700;
}

.info-modal-panel h2 {
  margin: 0;
  font-size: 1.2rem;
}

.info-modal-body {
  display: grid;
  gap: 1rem;
  min-height: 0;
  overflow: auto;
  padding: 1.2rem 1.35rem 1.35rem;
  color: var(--wa-ink-light);
  font-size: 0.92rem;
}

.info-modal-body h3,
.info-modal-body p {
  margin: 0;
}

.info-modal-body h3 {
  color: var(--wa-ink);
  font-size: 0.95rem;
}

.info-lead {
  color: var(--wa-ink);
  font-size: 1rem;
  font-weight: 700;
}

.info-modal-body ul {
  margin: 0.45rem 0 0;
  padding-left: 1.2rem;
}

.info-modal-body li + li {
  margin-top: 0.3rem;
}

.info-diagram {
  margin-top: 0.65rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 8px;
  background: var(--wa-bg);
  padding: 0.85rem;
}

.info-diagram pre {
  margin: 0;
  color: var(--wa-ink);
  font: 700 0.9rem/1.35 ui-monospace, SFMono-Regular, Consolas, monospace;
}

.rotation-demo {
  display: grid;
  grid-template-columns: minmax(9rem, 1fr) auto minmax(9rem, 1fr);
  gap: 0.85rem;
  align-items: center;
  margin-top: 0.7rem;
}

.rotation-arrow {
  color: var(--wa-orange-dark);
  font-size: 1.6rem;
  font-weight: 700;
}

.mini-tree {
  position: relative;
  min-height: 9.5rem;
  border: 1px solid var(--wa-gray-light);
  border-radius: 8px;
  background: var(--wa-bg);
}

.mini-node {
  position: absolute;
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border: 2px solid rgba(204, 122, 0, 0.34);
  border-radius: 999px;
  background: var(--wa-white);
  color: var(--wa-ink);
  font-weight: 700;
  transform: translate(-50%, -50%);
}

.mini-root {
  left: 62%;
  top: 22%;
}

.mini-left {
  left: 44%;
  top: 52%;
}

.mini-left-left {
  left: 28%;
  top: 82%;
}

.mini-right {
  left: 70%;
  top: 62%;
}

.mini-tree.is-balanced .mini-root {
  left: 50%;
  top: 24%;
}

.mini-tree.is-balanced .mini-left {
  left: 32%;
  top: 64%;
}

.mini-tree.is-balanced .mini-right {
  left: 68%;
  top: 64%;
}

.info-modal-body code {
  border-radius: 4px;
  background: var(--wa-bg);
  padding: 0.05rem 0.25rem;
}

@media (max-width: 900px) {
  .lesson-card,
  .lab-grid {
    grid-template-columns: 1fr;
  }

  .control-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .control-grid > .field,
  .field-expression-input,
  .field-wide {
    grid-column: span 2;
  }

  .board-heading {
    display: grid;
  }

  .legend {
    justify-content: flex-start;
  }

  .side-panel {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .status-card:nth-child(2) {
    border-right: 0;
    padding-right: 0;
  }
}

@media (max-width: 600px) {
  .tree-main {
    width: min(100% - 1rem, 72rem);
    padding-top: 4.5rem;
  }

  .control-grid,
  .side-panel {
    grid-template-columns: 1fr;
  }

  .control-grid > .field,
  .field-expression-input,
  .field-wide {
    grid-column: span 1;
  }

  .expression-tools {
    flex-wrap: wrap;
  }

  .status-card,
  .status-card:nth-child(2) {
    border-right: 0;
    border-bottom: 1px solid var(--wa-gray-light);
    padding-right: 0;
    padding-bottom: 0.75rem;
  }

  .status-card:last-child {
    border-bottom: 0;
    padding-bottom: 0;
  }

  .action-row > * {
    flex: 1 1 100%;
  }

  .tree-board {
    min-height: 26rem;
  }

  .tree-node {
    width: 3.35rem;
    height: 3.35rem;
    font-size: 0.58rem;
  }

  .node-meta {
    font-size: 0.42rem;
  }

  .rotation-demo {
    grid-template-columns: 1fr;
  }

  .rotation-arrow {
    text-align: center;
    transform: rotate(90deg);
  }
}