body.page-recursion .eyebrow {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 0.86rem;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

body.page-recursion .recursion-principles .formula-card {
  position: relative;
  padding-top: 48px;
}

.principle-number {
  position: absolute;
  top: 14px;
  left: 18px;
  display: inline-flex;
  width: 21px;
  height: 21px;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
}

.stack-anatomy {
  display: flex;
  max-width: 500px;
  flex-direction: column;
  gap: 5px;
  margin: 20px auto;
  padding: 16px 16px 10px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel-alt);
}

.stack-anatomy > div {
  display: grid;
  grid-template-columns: 90px 1fr;
  padding: 10px 13px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  border-radius: 6px;
  background: var(--panel);
}

.stack-anatomy small {
  grid-column: 1 / -1;
  color: var(--accent);
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.stack-anatomy span {
  color: var(--muted);
  font-size: 0.9rem;
}

.stack-anatomy p {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 0.78rem;
  text-align: center;
}

.recursion-visualizer {
  overflow: hidden;
  margin-top: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
}

.recursion-controls {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
}

.algorithm-switch {
  display: inline-flex;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel-alt);
}

.recursion-visualizer button {
  min-height: 38px;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--panel-alt);
  color: var(--text);
  cursor: pointer;
  font: inherit;
  font-weight: 650;
}

.algorithm-switch button {
  min-height: 34px;
  border-color: transparent;
  background: transparent;
}

.algorithm-switch button.is-selected {
  border-color: var(--line);
  background: var(--panel);
  color: var(--accent);
}

.recursion-visualizer button:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
}

.recursion-visualizer button:focus-visible,
.recursion-visualizer input:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.recursion-visualizer button:disabled {
  cursor: not-allowed;
  opacity: 0.38;
}

.n-control,
.memo-control {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
}

.n-control input {
  width: 150px;
  accent-color: var(--accent);
}

.n-control output,
.recursion-speed output {
  font-variant-numeric: tabular-nums;
}

.memo-control {
  margin-left: auto;
  font-size: 0.9rem;
}

.memo-control[hidden] {
  display: none;
}

.memo-control input {
  width: 17px;
  height: 17px;
  accent-color: var(--accent);
}

.recursion-stage {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(270px, 0.8fr);
  min-height: 470px;
  background: var(--panel-alt);
}

.call-tree-panel,
.call-stack-panel {
  min-width: 0;
  margin: 0;
  padding: 0;
  background: transparent;
}

.call-stack-panel {
  border-left: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 65%, var(--panel-alt));
}

.call-tree-panel > header,
.call-stack-panel > header {
  display: flex;
  min-height: 70px;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--line);
}

.call-tree-panel h4,
.call-stack-panel h4 {
  margin: 0;
  font-size: 1rem;
}

.panel-kicker,
.tree-hint,
.stack-direction {
  color: var(--muted);
  font-size: 0.7rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.call-tree-scroll {
  overflow: auto;
  height: 400px;
  background-image: radial-gradient(circle, color-mix(in srgb, var(--line) 65%, transparent) 1px, transparent 1px);
  background-size: 18px 18px;
}

.call-tree-scroll svg {
  display: block;
  margin: 0 auto;
}

.call-edge {
  stroke: var(--line);
  stroke-width: 1.5;
}

.call-node circle {
  fill: var(--panel);
  stroke: var(--line);
  stroke-width: 1.5;
}

.call-node text {
  fill: var(--muted);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 12px;
  font-weight: 700;
}

.call-node--active circle {
  fill: var(--accent-soft);
  stroke: var(--accent);
}

.call-node--active text {
  fill: var(--accent);
}

.call-node--current circle,
.call-node.is-current circle {
  fill: color-mix(in srgb, #e3a03b 48%, var(--panel));
  stroke: color-mix(in srgb, #b46f08 70%, var(--line));
  stroke-width: 3;
}

.call-node--current text,
.call-node.is-current text {
  fill: var(--text);
}

.call-node--done circle {
  fill: color-mix(in srgb, #278651 30%, var(--panel));
  stroke: color-mix(in srgb, #278651 60%, var(--line));
}

.call-node--done text {
  fill: color-mix(in srgb, #17653b 80%, var(--text));
}

:root[data-theme="dark"] .call-node--done text {
  fill: #a6dbb9;
}

.call-node--cached circle {
  fill: color-mix(in srgb, #7252b5 35%, var(--panel));
  stroke: color-mix(in srgb, #7252b5 70%, var(--line));
}

.call-node--cached text {
  fill: color-mix(in srgb, #7252b5 80%, var(--text));
}

:root[data-theme="dark"] .call-node--cached text {
  fill: #cab8f2;
}

.call-stack {
  display: flex;
  height: 400px;
  flex-direction: column;
  gap: 7px;
  overflow-y: auto;
  padding: 12px;
}

.stack-frame {
  position: relative;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--muted);
  border-radius: 7px;
  background: var(--panel);
}

.stack-frame--top {
  border-left-color: var(--accent);
  box-shadow: inset 0 0 0 1px color-mix(in srgb, var(--accent) 15%, transparent);
}

.stack-frame.is-current {
  border-left-color: #c27b17;
  background: color-mix(in srgb, #e3a03b 8%, var(--panel));
}

.stack-frame > div {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
}

.stack-frame > div span {
  color: var(--muted);
  font-size: 0.76rem;
}

.stack-frame p {
  margin: 3px 0 0;
  color: var(--muted);
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 0.75rem;
  line-height: 1.35;
}

.stack-frame > small {
  position: absolute;
  top: -6px;
  left: 8px;
  padding: 0 4px;
  background: var(--panel);
  color: var(--accent);
  font-size: 0.58rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.empty-stack {
  display: flex;
  min-height: 130px;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: 20px;
  border: 1px dashed var(--line);
  border-radius: 7px;
  color: var(--muted);
  text-align: center;
}

.empty-stack span {
  max-width: 260px;
  margin-top: 4px;
  font-size: 0.82rem;
}

.recursion-status {
  display: flex;
  min-height: 75px;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
  padding: 14px 18px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.recursion-status p {
  margin: 0;
  font-weight: 650;
}

.recursion-status span {
  flex: 0 0 auto;
  color: var(--muted);
  font-size: 0.84rem;
  font-variant-numeric: tabular-nums;
}

.recursion-transport {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 13px 18px;
}

.transport-buttons {
  display: flex;
  gap: 5px;
}

.recursion-visualizer .recursion-play {
  min-width: 105px;
  border-color: var(--accent);
  background: var(--accent);
  color: var(--bg);
}

.recursion-visualizer .recursion-play:hover:not(:disabled) {
  background: color-mix(in srgb, var(--accent) 86%, var(--text));
  color: var(--bg);
}

.recursion-speed {
  display: flex;
  align-items: center;
  gap: 9px;
  font-size: 0.84rem;
  font-weight: 700;
}

.recursion-speed input {
  width: 100px;
  accent-color: var(--accent);
}

.recursion-speed output {
  min-width: 34px;
  color: var(--muted);
}

.recursion-metrics {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  margin: 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.recursion-metrics div {
  padding: 9px 12px;
  border-right: 1px solid var(--line);
  text-align: center;
}

.recursion-metrics div:last-child {
  border-right: 0;
}

.recursion-metrics dt {
  color: var(--muted);
  font-size: 0.73rem;
}

.recursion-metrics dd {
  margin: 1px 0 0;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.recursion-code {
  overflow-x: auto;
  background: var(--code);
}

.recursion-code ol {
  min-width: max-content;
  margin: 0;
  padding: 12px 0 12px 48px;
  font-family: ui-monospace, SFMono-Regular, Consolas, monospace;
  font-size: 0.84rem;
}

.recursion-code li {
  padding: 2px 18px 2px 8px;
  border-left: 3px solid transparent;
  color: var(--muted);
}

.recursion-code li.is-current {
  border-left-color: var(--accent);
  background: var(--accent-soft);
  color: var(--text);
}

.recursion-code code {
  padding: 0;
  background: transparent;
}

.recursion-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  padding: 9px 18px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.74rem;
}

.recursion-legend span {
  display: inline-flex;
  align-items: center;
  gap: 5px;
}

.node-swatch {
  width: 12px;
  height: 12px;
  border: 1px solid var(--line);
  border-radius: 50%;
}

.node-swatch--current { background: color-mix(in srgb, #e3a03b 48%, var(--panel)); }
.node-swatch--active { background: var(--accent-soft); border-color: var(--accent); }
.node-swatch--done { background: color-mix(in srgb, #278651 30%, var(--panel)); }
.node-swatch--cached { background: color-mix(in srgb, #7252b5 35%, var(--panel)); }

.complexity-comparison {
  display: grid;
  grid-template-columns: 1fr auto 1fr auto 1fr;
  align-items: center;
  gap: 12px;
  margin-top: 18px;
}

.complexity-comparison article {
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  text-align: center;
}

.complexity-comparison span {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

.complexity-comparison strong {
  display: block;
  margin: 4px 0;
  color: var(--accent);
  font-size: 1.25rem;
}

.complexity-comparison p {
  margin: 0;
  color: var(--muted);
  font-size: 0.85rem;
}

.complexity-comparison > div {
  color: var(--muted);
  font-size: 1.4rem;
}

@media (max-width: 760px) {
  .recursion-controls {
    align-items: flex-start;
    flex-wrap: wrap;
  }

  .memo-control {
    width: 100%;
    margin-left: 0;
  }

  .recursion-stage {
    grid-template-columns: 1fr;
  }

  .call-stack-panel {
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .call-tree-scroll,
  .call-stack {
    height: 350px;
  }

  .recursion-transport {
    align-items: flex-start;
    flex-direction: column;
  }

  .transport-buttons {
    width: 100%;
  }

  .transport-buttons button {
    flex: 1;
  }

  .recursion-metrics {
    grid-template-columns: repeat(2, 1fr);
  }

  .recursion-metrics div:nth-child(2) {
    border-right: 0;
  }

  .recursion-metrics div:nth-child(-n + 2) {
    border-bottom: 1px solid var(--line);
  }

  .complexity-comparison {
    grid-template-columns: 1fr;
  }

  .complexity-comparison > div {
    transform: rotate(90deg);
    text-align: center;
  }
}

@media (max-width: 520px) {
  .stack-anatomy > div {
    grid-template-columns: 1fr;
  }

  .recursion-controls,
  .recursion-status,
  .recursion-transport {
    padding-right: 12px;
    padding-left: 12px;
  }

  .algorithm-switch {
    width: 100%;
  }

  .algorithm-switch button {
    flex: 1;
  }

  .n-control {
    width: 100%;
  }

  .n-control input {
    flex: 1;
    width: auto;
  }

  .call-tree-scroll,
  .call-stack {
    height: 315px;
  }

  .recursion-status {
    min-height: 102px;
    flex-direction: column;
    gap: 5px;
  }

  .recursion-play {
    min-width: 43px !important;
  }

  .recursion-play span {
    display: none;
  }
}

@media (prefers-reduced-motion: reduce) {
  .recursion-visualizer * {
    scroll-behavior: auto;
  }
}

@media print {
  .recursion-controls,
  .recursion-transport {
    display: none;
  }

  .recursion-stage {
    min-height: 360px;
  }

  .call-tree-scroll,
  .call-stack {
    height: 320px;
  }
}