:root {
  --paper: #f3f5f8;
  --surface: #ffffff;
  --ink: #111318;
  --muted: #69717e;
  --faint: #9299a5;
  --line: #cdd2db;
  --line-strong: #9299a5;
  --blue: #2455f5;
  --blue-soft: #eef2ff;
  --orange: #eb5b2a;
  --orange-soft: #fff0ea;
  --yellow: #ffdc5d;
  --yellow-soft: #fff8d7;
  --green: #0b9568;
  --green-soft: #eaf8f2;
  --red: #cc3d4a;
  --red-soft: #fff0f1;
  --sans: "Helvetica Neue", Helvetica, Arial, sans-serif;
  --mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html,
body {
  height: 100%;
  margin: 0;
}

body {
  display: flex;
  flex-direction: column;
  min-width: 320px;
  overflow: hidden;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}

button,
select,
input {
  font: inherit;
}

button,
select {
  color: inherit;
}

button:focus-visible,
select:focus-visible,
input:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: 2px;
}

.srOnly {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Course header */

.courseHeader {
  flex: 0 0 68px;
  display: grid;
  grid-template-columns: 230px minmax(0, 1fr) auto;
  align-items: stretch;
  background: var(--surface);
  border-bottom: 2px solid var(--ink);
  z-index: 10;
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;
  padding: 10px 16px;
  color: inherit;
  text-decoration: none;
  border-right: 1px solid var(--line);
}

.brandGlyph {
  display: grid;
  place-items: center;
  width: 46px;
  height: 34px;
  flex: 0 0 auto;
  background: var(--ink);
  color: white;
  font: 700 11px/1 var(--mono);
  letter-spacing: -0.06em;
}

.brandText {
  min-width: 0;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.courseMap {
  display: flex;
  min-width: 0;
  align-items: stretch;
  overflow-x: auto;
  scrollbar-width: none;
}

.courseMap::-webkit-scrollbar {
  display: none;
}

.tocGroup {
  display: contents;
}

.tocGroupTitle {
  display: none;
}

.tocEntry {
  position: relative;
  display: flex;
  flex: 1 0 86px;
  min-width: 0;
  align-items: center;
  gap: 6px;
  padding: 8px 10px 10px;
  border: 0;
  border-right: 1px solid var(--line);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  font-size: 11px;
  line-height: 1.2;
  text-align: left;
}

.tocEntry::after {
  content: "";
  position: absolute;
  right: 8px;
  bottom: 0;
  left: 8px;
  height: 4px;
  background: transparent;
}

.tocEntry:hover {
  background: var(--paper);
  color: var(--ink);
}

.tocEntry.active {
  color: var(--ink);
  font-weight: 700;
}

.tocEntry.active::after {
  background: var(--blue);
}

.tocNum {
  flex: 0 0 auto;
  color: var(--faint);
  font: 600 10px/1 var(--mono);
}

.tocTitle {
  min-width: 0;
}

.headerActions {
  position: relative;
  display: flex;
  min-width: 0;
  align-items: stretch;
}

.chapterPick {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
}

.chapterPick span {
  color: var(--muted);
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.chapterPick select {
  width: 100%;
  min-width: 0;
  padding: 4px 20px 4px 7px;
  border: 1px solid var(--line-strong);
  border-radius: 2px;
  background: white;
  font-size: 11px;
}

.githubButton {
  display: flex;
  min-width: 82px;
  align-items: center;
  justify-content: center;
  gap: 7px;
  padding: 0 13px;
  border-left: 1px solid var(--line);
  background: var(--ink);
  color: white;
  font-size: 11px;
  font-weight: 700;
  text-decoration: none;
  transition: background 140ms ease, color 140ms ease;
}

.githubButton:hover {
  background: var(--blue);
}

.githubButton:focus-visible {
  outline: 3px solid var(--blue);
  outline-offset: -5px;
}

.githubButton svg {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

/* Lesson and recorded steps */

.course {
  display: grid;
  flex: 1 1 auto;
  min-height: 0;
  grid-template-columns: 330px minmax(0, 1fr);
  overflow: hidden;
}

.lesson {
  position: relative;
  display: flex;
  min-height: 0;
  flex-direction: column;
  padding: 22px 22px 18px;
  overflow: hidden;
  background: var(--yellow-soft);
  border-right: 2px solid var(--ink);
}

.cardStack:empty::before {
  content: "Press Next to add a message.";
  display: grid;
  min-height: 72px;
  place-items: center;
  padding: 12px;
  border: 1px dashed var(--line-strong);
  color: var(--muted);
  font-size: 12px;
  line-height: 1.4;
  text-align: center;
}

.chapterControls {
  display: grid;
  flex: 0 0 auto;
  grid-template-columns: 30px 1fr 30px;
  align-items: center;
  gap: 8px;
}

.chapterControls > span {
  color: var(--muted);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-align: center;
  text-transform: uppercase;
}

.chevBtn {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  padding: 0;
  border: 1.5px solid var(--ink);
  border-radius: 50%;
  background: transparent;
  cursor: pointer;
}

.chevBtn svg {
  width: 12px;
  height: 12px;
}

.chevBtn:hover:not(:disabled) {
  background: var(--ink);
  color: white;
}

.chevBtn:disabled {
  cursor: default;
  opacity: 0.25;
}

.lesson h1 {
  margin: 22px 0 18px;
  font-size: clamp(32px, 3vw, 48px);
  font-weight: 800;
  letter-spacing: -0.055em;
  line-height: 0.94;
}

.law {
  display: flex;
  flex: 0 0 auto;
  flex-direction: column;
  gap: 8px;
  padding: 14px 0 16px;
  border-top: 2px solid var(--ink);
  border-bottom: 1px solid rgba(17, 19, 24, 0.25);
}

.law > span {
  color: var(--muted);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.law code {
  font: 700 15px/1.45 var(--mono);
  letter-spacing: -0.035em;
}

.narrStack {
  position: relative;
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  padding: 18px 4px 8px 0;
  scrollbar-color: var(--line-strong) transparent;
  scrollbar-width: thin;
}

.lessonLead {
  margin: 0;
  color: var(--muted);
  font-size: 14px;
  line-height: 1.55;
}

.lessonLead.compact {
  padding-bottom: 14px;
  border-bottom: 1px solid rgba(17, 19, 24, 0.18);
  font-size: 12.5px;
}

.lessonStep {
  margin-top: 16px;
}

.lessonStepMeta {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  color: var(--blue);
  font: 700 10px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.lessonStepMeta::before {
  content: "";
  width: 18px;
  height: 3px;
  background: currentColor;
}

.narr {
  margin: 0;
  font-size: 17px;
  font-weight: 500;
  letter-spacing: -0.014em;
  line-height: 1.48;
}

.narr.fresh {
  animation: lesson-in 220ms ease-out;
}

.lessonNote {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 13px;
  font-weight: 400;
  line-height: 1.45;
}

.lessonNote a {
  color: var(--blue);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.lessonNote a:hover {
  color: var(--ink);
}

@keyframes lesson-in {
  from {
    opacity: 0;
    transform: translateY(6px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.lessonHint {
  flex: 0 0 auto;
  padding-top: 12px;
  border-top: 1px solid rgba(17, 19, 24, 0.25);
  color: var(--muted);
  font: 11px/1.4 var(--mono);
}

#choiceBox {
  flex: 0 0 auto;
  max-height: 46%;
  overflow-y: auto;
  padding: 10px 0 12px;
}

.choices {
  display: grid;
  gap: 7px;
}

.choice,
.rewind {
  width: 100%;
  padding: 9px 10px;
  border: 1.5px solid var(--ink);
  border-radius: 2px;
  background: white;
  box-shadow: 3px 3px 0 var(--ink);
  cursor: pointer;
  font: 600 11px/1.4 var(--mono);
  text-align: left;
}

.choice:hover,
.rewind:hover {
  transform: translate(-1px, -1px);
  box-shadow: 4px 4px 0 var(--blue);
}

.choice .num {
  display: inline-grid;
  width: 20px;
  height: 20px;
  place-items: center;
  margin-right: 6px;
  background: var(--ink);
  color: white;
}

/* Recorded step viewer */

.runtime {
  display: flex;
  min-width: 0;
  min-height: 0;
  flex-direction: column;
  overflow: hidden;
  background: var(--surface);
}

.runtimeHeader {
  display: flex;
  flex: 0 0 42px;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 0 14px;
  border-bottom: 1px solid var(--line);
  background: var(--ink);
  color: white;
}

.runtimeHeader > div {
  display: flex;
  align-items: center;
  gap: 14px;
}

.runtimeTools {
  display: flex;
  min-width: 0;
  align-items: center;
  gap: 12px;
}

.archToggle {
  flex: 0 0 auto;
  padding: 6px 10px;
  border: 1px solid #6b7380;
  background: transparent;
  color: white;
  cursor: pointer;
  font: 700 10px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.archToggle:hover {
  border-color: white;
}

.archToggle[aria-expanded="true"] {
  background: var(--yellow);
  border-color: var(--yellow);
  color: var(--ink);
}

.runtimeStage {
  position: relative;
  display: flex;
  flex: 1 1 auto;
  min-height: 0;
  flex-direction: column;
  overflow: hidden;
}

.runtimeHeader strong {
  font: 700 12px/1 var(--mono);
}

.runtimeStatus {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: #cfd4dd;
  font: 10px/1 var(--mono);
}

.runtimeStatus i {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 0 3px rgba(11, 149, 104, 0.24);
}

.runtimeNote {
  overflow: hidden;
  color: #aeb5c0;
  font-size: 10.5px;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.phaseRail {
  display: grid;
  flex: 0 0 72px;
  grid-template-columns: repeat(4, 1fr);
  border-bottom: 2px solid var(--ink);
}

.phase {
  position: relative;
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  align-items: center;
  gap: 9px;
  min-width: 0;
  padding: 10px 12px;
  border-right: 1px solid var(--line);
  background: white;
  transition: background-color 150ms ease, color 150ms ease;
}

.phase:last-child {
  border-right: 0;
}

.phase > b {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  border: 1.5px solid var(--ink);
  border-radius: 50%;
  font: 700 11px/1 var(--mono);
}

.phase > span {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 4px;
}

.phase strong {
  font-size: 12px;
}

.phase code {
  overflow: hidden;
  color: var(--muted);
  font: 10px/1.2 var(--mono);
  text-overflow: ellipsis;
  white-space: nowrap;
}

.phase.active {
  background: var(--yellow);
}

.phase.active > b {
  background: var(--ink);
  color: white;
}

.phase.active code {
  color: var(--ink);
}

.runtimeGrid {
  display: grid;
  flex: 1 1 auto;
  min-height: 0;
  grid-template-columns: minmax(280px, 0.78fr) minmax(460px, 1.22fr);
  grid-template-rows: minmax(0, 1fr) minmax(150px, 0.42fr);
  grid-template-areas:
    "memory code"
    "world code";
  overflow: hidden;
}

/* Architecture slide-out. Overlay only. The three panes do not move. */

.archVeil {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  z-index: 4;
  padding: 0;
  border: 0;
  background: rgba(17, 19, 24, 0.28);
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
}

.runtime.archOpen .archVeil {
  opacity: 1;
  pointer-events: auto;
}

.archSheet {
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  z-index: 5;
  display: flex;
  width: min(420px, 100%);
  flex-direction: column;
  overflow: hidden;
  background: var(--paper);
  border-left: 2px solid var(--ink);
  transform: translateX(104%);
  transition: transform 220ms ease;
  pointer-events: none;
}

.runtime.archOpen .archSheet {
  transform: translateX(0);
  pointer-events: auto;
}

.archSheet.onceLayout {
  width: min(720px, 100%);
}

.archSheet.toolLayout {
  width: min(880px, 100%);
}

.archSheet.loopLayout {
  width: min(640px, 100%);
}

.archSheet.workLayout {
  width: min(640px, 100%);
}

.archSheet.savedLayout {
  width: min(720px, 100%);
}

.archSheet.agentsLayout {
  width: min(720px, 100%);
}

.archSheet.onceLayout .archFigure,
.archSheet.loopLayout .archFigure,
.archSheet.workLayout .archFigure,
.archSheet.savedLayout .archFigure,
.archSheet.agentsLayout .archFigure {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.archHead {
  display: flex;
  flex: 0 0 auto;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 16px 12px;
  border-bottom: 1.5px solid var(--ink);
  background: white;
}

.archHead span {
  display: block;
  color: var(--muted);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.archHead strong {
  display: block;
  margin-top: 4px;
  font-size: 16px;
  letter-spacing: -0.03em;
}

#archClose {
  flex: 0 0 auto;
  padding: 6px 10px;
  border: 1.5px solid var(--ink);
  background: white;
  cursor: pointer;
  font: 700 11px/1 var(--sans);
}

#archClose:hover {
  background: var(--ink);
  color: white;
}

.archPoint {
  flex: 0 0 auto;
  margin: 0;
  padding: 12px 16px 10px;
  color: var(--ink);
  font-size: 13.5px;
  line-height: 1.45;
}

.archFigure {
  flex: 1 1 auto;
  min-height: 0;
  padding: 0 16px 16px;
  overflow: auto;
}

.archMap {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0;
  padding: 12px;
  border: 1.5px solid var(--ink);
  background: white;
}

.archBox {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 9px 11px;
  border: 1.5px solid var(--ink);
  background: white;
}

.archBox.model {
  background: var(--orange-soft);
}

.archBox.messages {
  background: var(--blue-soft);
}

.archBox.world {
  background: var(--green-soft);
}

.archBox.store {
  background: var(--yellow-soft);
}

.archBox.child {
  background: var(--paper);
}

.archKind {
  color: var(--muted);
  font: 700 9px/1 var(--mono);
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.archBox b {
  font-size: 13px;
  letter-spacing: -0.02em;
}

.archBox small {
  color: var(--muted);
  font-size: 11px;
  line-height: 1.3;
}

.archBox.hot {
  background: var(--yellow);
  box-shadow: 3px 3px 0 var(--ink);
}

.archBox.hot small,
.archBox.hot .archKind {
  color: var(--ink);
}

.archBox.emph:not(.off) {
  border-width: 2px;
}

.archBox.off,
.archDown.off,
.archReturn.off {
  opacity: 0.38;
}

.archBox.off {
  border-style: dashed;
  background: white;
}

.archBox.hide,
.archDown.hide,
.archReturn.hide {
  display: none;
}

.archDown {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: 7px 0 6px;
  color: var(--muted);
  font: 700 9px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.archDown::before {
  content: "";
  width: 1.5px;
  height: 12px;
  background: var(--ink);
}

.archDown::after {
  content: "";
  border: 5px solid transparent;
  border-top-color: var(--ink);
}

.archDown.hot {
  color: var(--ink);
}

.archSplit {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  align-items: start;
}

.archCol {
  display: flex;
  min-width: 0;
  flex-direction: column;
}

.archCol .archBox + .archBox {
  margin-top: 8px;
}

.archReturn {
  position: relative;
  margin-top: 12px;
  padding: 9px 10px;
  border: 1.5px solid var(--ink);
  background: var(--yellow-soft);
  color: var(--ink);
  font: 700 11px/1.35 var(--mono);
  text-align: center;
}

.archReturn.hot {
  background: var(--yellow);
  box-shadow: 3px 3px 0 var(--ink);
}

.archReturn.cut {
  background: white;
  border-style: dashed;
  color: var(--muted);
}

.archReturnGo,
.archReturnStop {
  display: none;
}

.archLegend {
  margin: 10px 2px 0;
  color: var(--muted);
  font-size: 11px;
  line-height: 1.35;
}

.archOnce {
  display: flex;
  flex-direction: column;
  gap: 18px;
  padding: 28px 22px 20px;
  border: 1.5px solid var(--ink);
  background: white;
}

.onceRow {
  display: flex;
  align-items: stretch;
  gap: 8px;
}

.archOnce .archBox {
  flex: 1 1 0;
  justify-content: center;
  min-width: 0;
  padding: 14px 12px;
  text-align: center;
}

.archOnce .archBox.messages {
  background: var(--paper);
}

.archOnce .archBox.program {
  flex: 1.15 1 0;
  background: var(--blue-soft);
}

.archOnce .archBox.program b {
  color: var(--blue);
  font: 700 13px/1.25 var(--mono);
  letter-spacing: -0.03em;
}

.archOnce .archBox.program small {
  color: var(--blue);
}

.archOnce .archBox.model {
  background: var(--orange-soft);
}

.archOnce .archBox.model b,
.archOnce .archBox.model small {
  color: var(--orange);
}

.archOnce .archBox.world {
  background: var(--green-soft);
}

.archOnce .archBox.world b,
.archOnce .archBox.world small {
  color: var(--green);
}

.archOnce.four .archBox {
  padding: 12px 8px;
}

.archOnce.four .archBox b {
  font-size: 12px;
}

.archOnce .archBox.hot {
  background: var(--yellow);
}

.archOnce .archBox.hot b,
.archOnce .archBox.hot small {
  color: var(--ink);
}

.archOnce.choose .archBox {
  border-radius: 12px;
}

.archOnce.choose .archBox.tools {
  flex: 1.3 1 0;
  background: var(--blue-soft);
}

.archOnce.choose .archBox.tools b,
.archOnce.choose .archBox.tools small {
  color: var(--blue);
}

.archOnce.choose .archBox.tools.hot {
  background: var(--yellow);
}

.archOnce.choose .archBox.tools.hot b,
.archOnce.choose .archBox.tools.hot small {
  color: var(--ink);
}

.onceArrow {
  position: relative;
  flex: 0 0 22px;
  align-self: center;
  height: 2px;
  background: var(--line-strong);
}

.onceArrow::after {
  content: "";
  position: absolute;
  top: 50%;
  right: -1px;
  border: 5px solid transparent;
  border-left-color: var(--line-strong);
  transform: translateY(-50%);
}

.onceArrow.hot {
  background: var(--ink);
}

.onceArrow.hot::after {
  border-left-color: var(--ink);
}

.onceNote {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.4;
  text-align: center;
}

.archLoop {
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 22px 18px 18px;
  border: 1.5px solid var(--ink);
  background: white;
}

.loopChart {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(196px, 250px) minmax(0, 1fr) 54px;
  grid-template-rows: auto 16px auto 16px auto 18px auto;
  column-gap: 10px;
  align-items: stretch;
}

.loopChart > .archBox[data-arch="messages"] { grid-column: 2; grid-row: 1; }
.loopChart > .flowDown[data-arch="call"] { grid-column: 2; grid-row: 2; }
.loopChart > .archBox[data-arch="program"] { grid-column: 2; grid-row: 3; }
.loopChart > .flowDown:not([data-arch]):not(.loopFork) { grid-column: 2; grid-row: 4; }
.loopChart > .archBox[data-arch="model"] { grid-column: 2; grid-row: 5; }
.loopChart > .loopFork { grid-column: 2; grid-row: 6; }
.loopSplit {
  grid-column: 1 / 4;
  grid-row: 7;
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  padding-top: 10px;
}
.loopSplit::before {
  content: "";
  position: absolute;
  top: 0;
  left: 25%;
  width: 50%;
  height: 1.5px;
  background: var(--line-strong);
}
.loopSplit .archBox {
  position: relative;
}
.loopSplit .archBox::before {
  content: "";
  position: absolute;
  top: -10px;
  left: 50%;
  width: 1.5px;
  height: 10px;
  background: var(--line-strong);
  transform: translateX(-50%);
}
.loopBack {
  grid-column: 4;
  grid-row: 3 / 8;
}

.loopChart .archBox {
  justify-content: center;
  text-align: center;
}

.loopChart .archBox.messages,
.loopChart .archBox.stop {
  background: var(--paper);
}

.loopChart .archBox.program {
  background: var(--blue-soft);
}

.loopChart .archBox.program b {
  color: var(--blue);
  font: 700 13px/1.25 var(--mono);
  letter-spacing: -0.03em;
}

.loopChart .archBox.program small {
  color: var(--blue);
}

.loopChart .archBox.model {
  background: var(--orange-soft);
}

.loopChart .archBox.model b,
.loopChart .archBox.model small {
  color: var(--orange);
}

.loopChart .archBox.world {
  background: var(--green-soft);
}

.loopChart .archBox.world b,
.loopChart .archBox.world small {
  color: var(--green);
}

.loopChart .archBox.hot {
  background: var(--yellow);
}

.loopChart .archBox.hot b,
.loopChart .archBox.hot small {
  color: var(--ink);
}

.flowDown {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.flowDown::before {
  content: "";
  width: 1.5px;
  height: 100%;
  background: var(--line-strong);
}

.flowDown::after {
  content: "";
  position: absolute;
  bottom: -1px;
  border: 5px solid transparent;
  border-top-color: var(--line-strong);
}

.flowDown.hot::before {
  background: var(--ink);
}

.flowDown.hot::after {
  border-top-color: var(--ink);
}

.loopBack {
  position: relative;
  margin: 10px 0 36px 4px;
  border: 1.5px solid var(--green);
  border-left: 0;
  border-radius: 0 8px 8px 0;
}

.loopBack::before {
  content: "";
  position: absolute;
  top: -1px;
  left: -7px;
  border: 5px solid transparent;
  border-right-color: var(--green);
}

.loopBack i {
  position: absolute;
  left: 50%;
  top: 46%;
  color: var(--muted);
  font: 700 10px/1 var(--mono);
  font-style: normal;
  letter-spacing: 0.02em;
  white-space: nowrap;
  transform: translate(-50%, -50%) rotate(90deg);
}

.loopBack.hot {
  border-color: var(--ink);
}

.loopBack.hot::before {
  border-right-color: var(--ink);
}

.loopBack.hot i {
  color: var(--ink);
}

.archWork,
.archSaved,
.archAgents {
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 28px 22px 20px;
  border: 1.5px solid var(--ink);
  background: white;
}

.workChart {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 28px minmax(0, 1fr);
  grid-template-rows: auto 40px;
  column-gap: 8px;
  align-items: stretch;
}

.workChart > .archBox[data-arch="messages"] { grid-column: 1; grid-row: 1; }
.workChart > .onceArrow { grid-column: 2; grid-row: 1; width: 22px; justify-self: center; }
.workChart > .archBox[data-arch="model"] { grid-column: 3; grid-row: 1; }
.workChart > .workBack { grid-column: 1 / -1; grid-row: 2; }

.workChart .archBox {
  justify-content: center;
  min-width: 0;
  padding: 16px 14px;
  border-radius: 12px;
  text-align: center;
}

.workChart .archBox.messages {
  background: var(--paper);
}

.workChart .archBox.model {
  background: var(--orange-soft);
}

.workChart .archBox.model b,
.workChart .archBox.model small {
  color: var(--orange);
}

.workChart .archBox.hot {
  background: var(--yellow);
}

.workChart .archBox.hot b,
.workChart .archBox.hot small {
  color: var(--ink);
}

.workBack {
  position: relative;
}

.workBack::before {
  content: "";
  position: absolute;
  top: 0;
  right: 25%;
  bottom: 10px;
  left: 25%;
  border: 1.5px solid var(--line-strong);
  border-top: 0;
  border-radius: 0 0 10px 10px;
}

.workBack::after {
  content: "";
  position: absolute;
  top: -1px;
  left: calc(25% - 5px);
  border: 5px solid transparent;
  border-bottom-color: var(--line-strong);
}

.workBack i {
  position: absolute;
  left: 50%;
  bottom: -2px;
  color: var(--muted);
  font: 700 11px/1 var(--sans);
  font-style: normal;
  letter-spacing: 0.01em;
  white-space: nowrap;
  transform: translateX(-50%);
}

.workBack.hot::before {
  border-color: var(--ink);
}

.workBack.hot::after {
  border-bottom-color: var(--ink);
}

.workBack.hot i {
  color: var(--ink);
}

.savedChart {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: auto 52px auto;
  column-gap: 28px;
  align-items: stretch;
}

.savedRun {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 12px 12px 14px;
  border: 1.5px dashed var(--line-strong);
  border-radius: 14px;
  background: var(--paper);
}

.savedRun[data-arch="run1"] { grid-column: 1; grid-row: 1; }
.savedRun[data-arch="run2"] { grid-column: 2; grid-row: 1; }

.savedRunLabel {
  color: var(--muted);
  font: 700 12px/1 var(--sans);
}

.savedRun .archBox {
  justify-content: center;
  padding: 12px 10px;
  border-radius: 10px;
  background: white;
  text-align: center;
}

.savedRun.hot {
  border-color: var(--ink);
  border-style: solid;
  background: var(--yellow-soft);
}

.savedChart .archBox.hot {
  background: var(--yellow);
}

.savedChart .archBox.hot b,
.savedChart .archBox.hot small {
  color: var(--ink);
}

.savedLinks {
  grid-column: 1 / -1;
  grid-row: 2;
  position: relative;
}

.savedElbow {
  position: absolute;
  top: 0;
  bottom: 0;
}

.savedElbow.out {
  left: 25%;
  right: 50%;
  border-left: 1.5px solid var(--line-strong);
  border-bottom: 1.5px solid var(--line-strong);
  border-radius: 0 0 0 10px;
}

.savedElbow.in {
  left: 50%;
  right: 25%;
  border-right: 1.5px solid var(--line-strong);
  border-bottom: 1.5px solid var(--line-strong);
  border-radius: 0 0 10px 0;
}

.savedElbow.out::after {
  content: "";
  position: absolute;
  right: -5px;
  bottom: -5px;
  border: 5px solid transparent;
  border-top-color: var(--line-strong);
}

.savedElbow.in::after {
  content: "";
  position: absolute;
  top: -1px;
  right: -6px;
  border: 5px solid transparent;
  border-bottom-color: var(--line-strong);
}

.savedElbow i {
  position: absolute;
  top: 6px;
  color: var(--muted);
  font: 700 11px/1 var(--mono);
  font-style: normal;
  white-space: nowrap;
}

.savedElbow.out i {
  left: 10px;
}

.savedElbow.in i {
  right: 10px;
}

.savedElbow.hot {
  border-color: var(--ink);
}

.savedElbow.hot::after {
  border-top-color: var(--ink);
}

.savedElbow.in.hot::after {
  border-top-color: transparent;
  border-bottom-color: var(--ink);
}

.savedElbow.hot i {
  color: var(--ink);
}

.savedChart > .archBox.store {
  grid-column: 1 / -1;
  grid-row: 3;
  justify-self: center;
  width: min(280px, 86%);
  justify-content: center;
  padding: 14px 16px;
  border-radius: 12px;
  background: var(--green-soft);
  text-align: center;
}

.savedChart > .archBox.store b,
.savedChart > .archBox.store small {
  color: var(--green);
}

.savedChart > .archBox.store.hot b,
.savedChart > .archBox.store.hot small {
  color: var(--ink);
}

.agentsChart {
  display: grid;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: auto 16px auto 18px auto;
  column-gap: 20px;
  justify-items: stretch;
}

.agentsChart > .archBox[data-arch="parent"] {
  grid-column: 1 / -1;
  grid-row: 1;
  justify-self: center;
  width: min(280px, 100%);
}

.agentsChart > .flowDown {
  grid-column: 1 / -1;
  grid-row: 2;
}

.agentsChart > .archBox[data-arch="child"] {
  grid-column: 1 / -1;
  grid-row: 3;
  justify-self: center;
  width: min(320px, 100%);
}

.agentsFork {
  grid-column: 1 / -1;
  grid-row: 4;
  position: relative;
}

.agentsFork::before {
  content: "";
  position: absolute;
  left: 50%;
  top: 0;
  width: 1.5px;
  height: 8px;
  background: var(--line-strong);
  transform: translateX(-50%);
}

.agentsFork::after {
  content: "";
  position: absolute;
  top: 8px;
  left: 25%;
  right: 25%;
  height: 1.5px;
  background: var(--line-strong);
}

.agentsKids {
  grid-column: 1 / -1;
  grid-row: 5;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.agentsKids .archBox {
  position: relative;
}

.agentsKids .archBox::before {
  content: "";
  position: absolute;
  top: -10px;
  left: 50%;
  width: 1.5px;
  height: 10px;
  background: var(--line-strong);
  transform: translateX(-50%);
}

.agentsChart .archBox {
  justify-content: center;
  min-width: 0;
  padding: 14px 12px;
  border-radius: 12px;
  text-align: center;
}

.agentsChart .archBox.messages {
  background: var(--paper);
}

.agentsChart .archBox.model {
  background: var(--orange-soft);
}

.agentsChart .archBox.model b,
.agentsChart .archBox.model small {
  color: var(--orange);
}

.agentsChart .archBox.world {
  background: var(--green-soft);
}

.agentsChart .archBox.world b,
.agentsChart .archBox.world small {
  color: var(--green);
}

.agentsChart .archBox.hot {
  background: var(--yellow);
}

.agentsChart .archBox.hot b,
.agentsChart .archBox.hot small {
  color: var(--ink);
}

.memoryPane,
.codePane,
.worldPane {
  position: relative;
  display: flex;
  min-width: 0;
  min-height: 0;
  flex-direction: column;
  overflow: hidden;
  background: white;
}

.memoryPane {
  grid-area: memory;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.codePane {
  grid-area: code;
  padding: 0 12px 12px;
}

.worldPane {
  grid-area: world;
  border-right: 1px solid var(--line);
  background: #f8fafc;
}

.memoryPane.active {
  box-shadow: inset 4px 0 0 var(--blue);
}

.codePane.active {
  box-shadow: inset 4px 0 0 var(--orange);
}

.worldPane.active {
  box-shadow: inset 4px 0 0 var(--green);
}

.paneHead {
  display: flex;
  flex: 0 0 44px;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 0 12px;
  border-bottom: 1px solid var(--line);
}

.codePane .paneHead {
  margin: 0 -12px;
}

.paneHead > div {
  display: flex;
  align-items: center;
  gap: 9px;
}

.paneHead strong {
  font-size: 12px;
}

.paneIndex {
  display: grid;
  width: 20px;
  height: 20px;
  place-items: center;
  background: var(--ink);
  color: white;
  font: 700 10px/1 var(--mono);
}

.tokens {
  color: var(--muted);
  font: 10.5px/1 var(--mono);
}

/* Message list */

.cardStack {
  display: flex;
  flex: 1 1 auto;
  min-height: 0;
  flex-direction: column;
  gap: 7px;
  padding: 10px 11px 12px;
  overflow-y: auto;
  scrollbar-color: var(--line-strong) transparent;
  scrollbar-width: thin;
}

.card {
  flex: 0 0 auto;
  padding: 9px 10px 10px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--line-strong);
  background: white;
  animation: card-in 180ms ease-out;
}

.card.user {
  border-left-color: var(--blue);
  background: var(--blue-soft);
}

.card.model {
  border-left-color: var(--orange);
  background: var(--orange-soft);
}

.card.tool {
  border-left-color: var(--green);
  background: var(--green-soft);
}

.card.system {
  background: #f5f6f8;
}

@keyframes card-in {
  from {
    opacity: 0;
    transform: translateY(7px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.cardHead {
  display: flex;
  align-items: center;
}

.chip {
  color: var(--muted);
  font: 700 9px/1 var(--mono);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.card.user .chip {
  color: var(--blue);
}

.card.model .chip {
  color: var(--orange);
}

.card.tool .chip {
  color: var(--green);
}

.cardBody {
  margin-top: 6px;
  color: var(--ink);
  font: 11.5px/1.45 var(--mono);
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}

mark.false {
  padding: 0 2px;
  background: var(--red-soft);
  color: var(--red);
  text-decoration: underline;
  text-decoration-thickness: 2px;
}

/* Executable code */

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

.codeFile {
  margin-left: auto;
  padding: 4px 7px;
  border: 1px solid var(--line-strong);
  background: var(--paper);
  font: 700 10px/1 var(--mono);
}

.codeCaption {
  flex: 0 0 auto;
  max-width: 74ch;
  margin: 8px 0 7px;
  color: var(--muted);
  font-size: 10.5px;
  line-height: 1.35;
}

#codePre {
  flex: 1 1 auto;
  min-width: 0;
  min-height: 0;
  margin: 0;
  padding: 6px 0;
  overflow: hidden;
  border: 1px solid var(--line);
  background: #fbfcfe;
  font-family: var(--mono);
  font-size: 12px;
  line-height: 1.4;
  tab-size: 2;
}

.ln {
  display: block;
  min-width: max-content;
  padding: 0 10px 0 0;
  border-left: 4px solid transparent;
  color: #252a33;
  white-space: pre;
}

.ln.active {
  border-left-color: var(--orange);
  background: var(--yellow);
}

.ln.active .gut {
  color: #7a6040;
}

.gut {
  display: inline-block;
  width: 3ch;
  margin: 0 1.7ch 0 0.7ch;
  color: #a0a7b2;
  font-weight: 400;
  text-align: right;
  user-select: none;
}

.tok-kw,
.tok-bi {
  color: #1d4ed8;
  font-weight: 600;
}

.tok-str {
  color: #0a7a56;
}

.tok-cm {
  color: #8b929e;
}

.tok-num {
  color: #c2410c;
}

.tok-fn {
  color: #111318;
  font-weight: 700;
}

.tok-const {
  color: #9a4a12;
}

.tok-brace {
  color: #eb5b2a;
  font-weight: 600;
}

/* World views */

#worldBody {
  flex: 1 1 auto;
  min-height: 0;
  padding: 10px 12px 12px;
  overflow-y: auto;
}

.worldCap {
  margin: 0 0 8px;
  color: var(--muted);
  font-size: 9px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.idleWorld {
  display: grid;
  min-height: 72px;
  place-items: center;
  padding: 12px;
  border: 1px dashed var(--line-strong);
  color: var(--muted);
  font-size: 11.5px;
  line-height: 1.45;
  text-align: center;
}

.singleTool {
  overflow: hidden;
  border: 1px solid var(--line);
  background: white;
}

.toolFunction,
.toolRunState,
.toolDatum {
  display: flex;
  min-height: 40px;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 8px 9px;
  border-bottom: 1px solid var(--line);
}

.singleTool > :last-child {
  border-bottom: 0;
}

.toolFunction {
  background: var(--ink);
  color: white;
}

.toolFunction span,
.toolRunState span,
.toolDatum span {
  color: var(--faint);
  font-size: 8.5px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.toolFunction code,
.toolDatum code {
  font: 700 9.5px/1.35 var(--mono);
}

.toolRunState strong {
  color: var(--muted);
  font: 700 10px/1 var(--mono);
  text-transform: uppercase;
}

.toolRunState.requested strong {
  color: var(--orange);
}

.toolRunState.done strong,
.toolDatum.result code {
  color: var(--green);
}

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

.toolDatum code {
  overflow-wrap: anywhere;
}

.noLoopCount {
  margin-top: 7px;
  padding: 7px 9px;
  border: 1px solid var(--line);
  background: var(--yellow-soft);
  color: var(--muted);
  font-size: 9px;
  line-height: 1.4;
}

.noLoopCount b {
  color: var(--ink);
  font-family: var(--mono);
}

.fileTree {
  padding: 6px 8px;
  border: 1px solid var(--line);
  background: white;
}

.fileRow {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 3px 0;
  font: 10.5px/1.25 var(--mono);
}

.fileDot {
  width: 7px;
  height: 7px;
  flex: 0 0 auto;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: white;
}

.fileDot.read {
  border-color: var(--blue);
  background: var(--blue);
}

.fileDot.modified {
  border-color: var(--orange);
  background: var(--orange);
}

.fileStatus {
  margin-left: auto;
  color: var(--muted);
  font-size: 8.5px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.term {
  min-height: 52px;
  margin-top: 7px;
  padding: 7px 9px;
  border: 1px solid var(--line);
  background: var(--ink);
  color: #f0f3f8;
  font: 10.5px/1.48 var(--mono);
}

.tline {
  white-space: pre-wrap;
}

.tline.ok {
  color: #68e0ad;
}

.tline.err {
  color: #ff8b94;
}

.tline.dim {
  color: #929aa8;
}

.meterNum {
  margin-top: 2px;
  font-size: 26px;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.meterNum span {
  color: var(--muted);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0;
}

.meterBar {
  height: 11px;
  margin: 10px 0 8px;
  border: 1px solid var(--ink);
  background: white;
}

.meterFill {
  height: 100%;
  background: var(--blue);
  transition: width 220ms ease;
}

.meterFill.danger {
  background: var(--red);
}

.meterNote {
  color: var(--muted);
  font: 9.5px/1 var(--mono);
}

.wsRow {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 7px;
}

.wsChip {
  padding: 3px 5px;
  border: 1px solid var(--line);
  background: white;
  color: var(--muted);
  font: 9px/1 var(--mono);
}

.wsChip.on {
  border-color: var(--ink);
  background: var(--ink);
  color: white;
}

.phone {
  display: flex;
  min-height: 62px;
  flex-direction: column;
  gap: 6px;
  padding: 7px;
  border: 1px solid var(--line);
  background: white;
}

.bubble {
  max-width: 86%;
  padding: 6px 8px;
  font-size: 10.5px;
  line-height: 1.35;
}

.bubble.in {
  align-self: flex-start;
  background: var(--paper);
}

.bubble.out {
  align-self: flex-end;
  background: var(--blue);
  color: white;
}

.bubbleDim {
  margin: auto;
  color: var(--muted);
  font-size: 10px;
  text-align: center;
}

.cronBadge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 7px;
  padding: 4px 6px;
  border: 1px solid var(--line);
  background: white;
  font: 9.5px/1.2 var(--mono);
}

.cronDot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--green);
}

/* Durable memory */

.memoryStore {
  border: 1px solid var(--line);
  background: white;
}

.memoryStoreHead {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 8px;
  border-bottom: 1px solid var(--line);
}

.memoryStoreHead strong {
  font: 700 10px/1 var(--mono);
}

.memoryStoreHead span {
  color: var(--green);
  font: 700 8.5px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.memoryRecord {
  display: grid;
  grid-template-columns: 0.7fr 1fr;
  gap: 8px;
  padding: 7px 8px;
  font: 10px/1.3 var(--mono);
}

.memoryRecord span {
  color: var(--muted);
}

.memoryRecord strong {
  color: var(--green);
}

.memoryEmpty {
  padding: 10px 8px;
  color: var(--muted);
  font: 9.5px/1.3 var(--mono);
  text-align: center;
}

.memorySession {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  margin-top: 7px;
  padding: 6px 8px;
  border: 1px solid var(--line);
  background: var(--blue-soft);
}

.memorySession span {
  color: var(--blue);
  font: 700 9px/1 var(--mono);
  text-transform: uppercase;
}

.memorySession code {
  overflow: hidden;
  font: 9.5px/1 var(--mono);
  text-overflow: ellipsis;
  white-space: nowrap;
}

/* Nested agent loops */

.agentRoster {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 5px;
}

.agentUnit {
  display: grid;
  min-width: 0;
  grid-template-columns: 20px minmax(0, 1fr);
  gap: 5px;
  padding: 6px;
  border: 1px solid var(--line);
  background: white;
}

.agentUnit.running {
  border-color: var(--orange);
  background: var(--orange-soft);
}

.agentUnit.waiting {
  border-color: var(--blue);
  background: var(--blue-soft);
}

.agentUnit.done {
  border-color: var(--green);
  background: var(--green-soft);
}

.agentAvatar {
  display: grid;
  width: 20px;
  height: 20px;
  place-items: center;
  border-radius: 50%;
  background: var(--ink);
  color: white;
  font: 700 9px/1 var(--mono);
}

.agentIdentity {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 2px;
}

.agentIdentity strong,
.agentIdentity small {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.agentIdentity strong {
  font-size: 9.5px;
}

.agentIdentity small {
  color: var(--muted);
  font-size: 8px;
}

.agentState {
  grid-column: 1 / -1;
  color: var(--muted);
  font: 700 8px/1 var(--mono);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.agentUnit.running .agentState {
  color: var(--orange);
}

.agentUnit.waiting .agentState {
  color: var(--blue);
}

.agentUnit.done .agentState {
  color: var(--green);
}

.delegateLog {
  display: grid;
  max-height: 58px;
  gap: 3px;
  margin-top: 7px;
  overflow-y: auto;
}

.delegateEvent {
  padding-left: 8px;
  border-left: 2px solid var(--line-strong);
  color: var(--muted);
  font: 8.5px/1.3 var(--mono);
}

/* Controls */

.controls {
  position: relative;
  flex: 0 0 62px;
  background: white;
  border-top: 2px solid var(--ink);
}

.progressTrack {
  position: absolute;
  top: -2px;
  right: 0;
  left: 0;
  height: 4px;
  background: transparent;
}

.progressFill {
  width: 0;
  height: 100%;
  background: var(--blue);
  transition: width 180ms ease;
}

.controlRow {
  display: flex;
  height: 100%;
  align-items: center;
  gap: 15px;
  padding: 8px 16px;
}

.buttons {
  display: flex;
  gap: 7px;
}

.controlRow button {
  min-width: 68px;
  padding: 8px 14px;
  border: 1.5px solid var(--ink);
  border-radius: 2px;
  background: white;
  cursor: pointer;
  font-size: 12px;
  font-weight: 700;
}

.controlRow button:hover:not(:disabled) {
  background: var(--paper);
}

.controlRow button:disabled {
  cursor: default;
  opacity: 0.3;
}

.controlRow .primary {
  min-width: 96px;
  background: var(--blue);
  color: white;
}

.controlRow .primary:hover:not(:disabled) {
  background: #1745db;
}

.speed {
  display: flex;
  margin-left: auto;
  align-items: center;
  gap: 7px;
  color: var(--muted);
  font-size: 10px;
}

.speed input {
  width: 82px;
  accent-color: var(--blue);
}

.stepInd {
  min-width: 74px;
  color: var(--ink);
  font: 700 10px/1 var(--mono);
  text-align: center;
}

.hint {
  color: var(--muted);
  font-size: 10px;
}

/* Recap. Same split as the course: the words, then the loop. */

#closingPanel {
  display: flex;
  flex: 1 1 auto;
  min-height: 0;
  overflow: auto;
  background: var(--paper);
}

.closingPage {
  display: grid;
  flex: 1 1 auto;
  min-height: 0;
  width: min(1280px, 100%);
  margin: 0 auto;
  padding: 26px 36px 18px;
  grid-template-columns: minmax(280px, 0.82fr) minmax(420px, 1.18fr);
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "lead figure"
    "roles figure"
    "watched watched";
  gap: 16px 28px;
}

.closingLead {
  grid-area: lead;
  min-width: 0;
}

#closingPanel h2 {
  margin: 0;
  font-size: clamp(34px, 4.1vw, 58px);
  letter-spacing: -0.055em;
  line-height: 0.96;
}

#closingPanel .lede {
  max-width: 36ch;
  margin: 14px 0 0;
  color: var(--ink);
  font-size: 16px;
  line-height: 1.45;
}

.closingLinks {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  margin: 14px 0 0;
}

.closingLinks a {
  color: var(--blue);
  font-size: 13.5px;
  font-weight: 700;
  letter-spacing: -0.02em;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.closingLinks a:hover {
  color: var(--ink);
}

.closingFigure {
  grid-area: figure;
  display: flex;
  min-width: 0;
  min-height: 0;
  flex-direction: column;
  background: #111318;
  color: #e8eaee;
}

.closingWhile {
  flex: 0 0 auto;
  margin: 0;
  padding: 14px 18px 10px;
  border-bottom: 1px solid #2a2e36;
  font: 700 15px/1.2 var(--mono);
}

.closingWhile b {
  color: #8db0ff;
  font-weight: 700;
}

.closingLoop {
  display: flex;
  min-height: 0;
  flex: 1 1 auto;
  flex-direction: column;
  margin: 0;
  padding: 0;
  list-style: none;
}

.closingLoop li {
  display: grid;
  flex: 1 1 auto;
  min-width: 0;
  align-content: center;
  grid-template-columns: 36px minmax(0, 1fr);
  grid-template-rows: auto auto auto;
  column-gap: 8px;
  padding: 12px 18px 12px 14px;
  border: 0;
  border-left: 3px solid transparent;
  background: transparent;
}

.closingLoop li:nth-child(1) { border-left-color: var(--blue); }
.closingLoop li:nth-child(2) { border-left-color: var(--orange); }
.closingLoop li:nth-child(3) { border-left-color: var(--green); }
.closingLoop li:nth-child(4) { border-left-color: var(--yellow); }

.closingLoop b {
  grid-row: 1 / span 3;
  padding-top: 2px;
  color: #8b929e;
  font: 700 12px/1 var(--mono);
}

.closingLoop strong {
  grid-column: 2;
  color: #fff;
  font-size: 15px;
  letter-spacing: -0.02em;
}

.closingLoop p {
  grid-column: 2;
  margin: 4px 0 0;
  color: #b4bac4;
  font-size: 13px;
  line-height: 1.4;
}

.closingLoop code {
  grid-column: 2;
  margin-top: 6px;
  color: #7dcea0;
  font: 12px/1.35 var(--mono);
}

.closingReturn {
  flex: 0 0 auto;
  margin: 0;
  padding: 12px 18px;
  background: var(--yellow);
  color: #111318;
  font: 700 13px/1.35 var(--mono);
}

.closingSplit {
  grid-area: roles;
  display: grid;
  align-content: start;
  gap: 10px;
  min-width: 0;
}

.closingSplit article {
  padding: 12px 14px 14px;
  border: 1px solid var(--line);
  border-left-width: 4px;
}

.closingSplit .roleModel {
  border-left-color: var(--orange);
  background: var(--orange-soft);
}

.closingSplit .roleProgram {
  border-left-color: var(--green);
  background: var(--green-soft);
}

.closingSplit h3 {
  margin: 0 0 5px;
  font-size: 14px;
}

.closingSplit p {
  margin: 0;
  color: var(--ink);
  font-size: 13px;
  line-height: 1.4;
}

.closingWatched {
  grid-area: watched;
  min-width: 0;
  padding: 0;
  border: 0;
  background: transparent;
}

.closingWatched h3 {
  margin: 0 0 10px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.closingWatched ol {
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 0;
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: lesson;
  border-top: 1.5px solid var(--ink);
}

.closingWatched li {
  display: flex;
  min-width: 0;
  flex-direction: column;
  gap: 5px;
  padding: 10px 12px 0 0;
  border: 0;
  color: var(--muted);
  font-size: 12.5px;
  line-height: 1.35;
  counter-increment: lesson;
}

.closingWatched li + li {
  padding-left: 12px;
  border-left: 1px solid var(--line);
}

.closingWatched span {
  color: var(--ink);
  font-size: 13.5px;
  font-weight: 700;
}

.closingWatched span::before {
  display: block;
  margin-bottom: 4px;
  color: var(--faint);
  content: counter(lesson);
  font: 700 11px/1 var(--mono);
}

body.isClosing #playBtn,
body.isClosing #nextBtn,
body.isClosing .hint,
body.isClosing .speed,
body.isClosing .stepInd {
  display: none;
}

/* Compact laptops keep the whole debugger in one viewport. */

@media (max-width: 1150px) {
  .courseHeader {
    grid-template-columns: 220px minmax(0, 1fr) auto;
  }

  .githubButton {
    min-width: 58px;
    padding: 0 12px;
  }

  .githubButton span {
    display: none;
  }

  .course {
    grid-template-columns: 260px minmax(0, 1fr);
  }

  .lesson {
    padding-right: 17px;
    padding-left: 17px;
  }

  .lesson h1 {
    font-size: 36px;
  }

  .runtimeNote {
    display: none;
  }

  .runtimeGrid {
    grid-template-columns: minmax(220px, 0.7fr) minmax(360px, 1.3fr);
  }

  .phase {
    grid-template-columns: 23px minmax(0, 1fr);
    gap: 6px;
    padding-right: 7px;
    padding-left: 7px;
  }

  .phase > b {
    width: 22px;
    height: 22px;
  }

  .closingPage {
    padding: 20px 22px 16px;
    gap: 14px 18px;
  }

  #closingPanel h2 {
    font-size: 36px;
  }
}

/* Small screens become a vertical course. */

@media (max-width: 920px) {
  body {
    height: auto;
    min-height: 100dvh;
    padding-bottom: 76px;
    overflow: auto;
  }

  .courseHeader {
    position: sticky;
    top: 0;
  }

  .course {
    grid-template-columns: 280px minmax(0, 1fr);
    min-height: 820px;
  }

  .runtimeGrid {
    grid-template-columns: 1fr;
    grid-template-rows: 300px 520px 240px;
    grid-template-areas:
      "memory"
      "code"
      "world";
    overflow: visible;
  }

  .runtime {
    overflow: visible;
  }

  .runtimeStage {
    overflow: visible;
  }

  .archSheet {
    position: fixed;
    top: auto;
    right: 0;
    bottom: 62px;
    left: 0;
    width: 100%;
    max-height: min(72vh, 560px);
    border-left: 0;
    border-top: 2px solid var(--ink);
    transform: translateY(110%);
  }

  .runtime.archOpen .archSheet {
    transform: translateY(0);
  }

  .onceRow {
    flex-direction: column;
    align-items: stretch;
    gap: 6px;
  }

  .onceArrow {
    flex: 0 0 18px;
    width: 2px;
    height: 18px;
    align-self: center;
  }

  .onceArrow::after {
    top: auto;
    right: auto;
    bottom: -1px;
    left: 50%;
    border-left-color: transparent;
    border-top-color: var(--line-strong);
    transform: translateX(-50%);
  }

  .onceArrow.hot::after {
    border-left-color: transparent;
    border-top-color: var(--ink);
  }

  .workChart {
    grid-template-columns: 1fr;
    grid-template-rows: auto 18px auto 36px;
  }

  .workChart > .archBox[data-arch="messages"],
  .workChart > .onceArrow,
  .workChart > .archBox[data-arch="model"],
  .workChart > .workBack {
    grid-column: 1;
    grid-row: auto;
  }

  .workBack::before {
    left: 50%;
    right: 50%;
    width: 1.5px;
    border: 0;
    background: var(--line-strong);
    border-radius: 0;
  }

  .workBack::after {
    left: 50%;
    top: auto;
    bottom: 8px;
    border-bottom-color: transparent;
    border-top-color: var(--line-strong);
    transform: translateX(-50%);
  }

  .savedChart {
    grid-template-columns: 1fr;
    grid-template-rows: auto auto 44px auto;
    row-gap: 8px;
  }

  .savedRun[data-arch="run1"],
  .savedRun[data-arch="run2"],
  .savedLinks,
  .savedChart > .archBox.store {
    grid-column: 1;
    grid-row: auto;
  }

  .savedElbow.out,
  .savedElbow.in {
    left: 50%;
    right: auto;
    width: 1.5px;
    border: 0;
    border-radius: 0;
    background: var(--line-strong);
  }

  .savedElbow.out {
    left: 30%;
  }

  .savedElbow.in {
    left: 70%;
  }

  .savedElbow.out i {
    left: 8px;
    top: 50%;
    transform: translateY(-50%);
  }

  .savedElbow.in i {
    right: auto;
    left: 8px;
    top: 50%;
    transform: translateY(-50%);
  }

  .agentsChart {
    grid-template-columns: 1fr;
    grid-template-rows: none;
    gap: 8px;
  }

  .agentsChart > .archBox[data-arch="parent"],
  .agentsChart > .flowDown,
  .agentsChart > .archBox[data-arch="child"],
  .agentsFork,
  .agentsKids {
    grid-column: 1;
    grid-row: auto;
    width: 100%;
  }

  .agentsFork {
    height: 12px;
  }

  .agentsKids {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .loopChart {
    grid-template-columns: 1fr 1fr;
    grid-template-rows: none;
    gap: 8px;
  }

  .loopChart > .archBox[data-arch="messages"],
  .loopChart > .flowDown,
  .loopChart > .archBox[data-arch="program"],
  .loopChart > .archBox[data-arch="model"],
  .loopSplit,
  .loopBack {
    grid-column: 1 / -1;
    grid-row: auto;
  }

  .loopBack {
    height: auto;
    margin: 4px 0 0;
    padding: 6px 0 0;
    border: 0;
    text-align: center;
  }

  .loopBack::before {
    display: none;
  }

  .loopBack i {
    position: static;
    transform: none;
  }

  .archVeil {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 62px;
    left: 0;
  }

  .memoryPane,
  .worldPane {
    border-right: 0;
  }

  #codePre {
    overflow: auto;
  }

  .controls {
    position: sticky;
    bottom: 0;
    z-index: 20;
  }

  .closingPage {
    display: flex;
    flex-direction: column;
    height: auto;
    padding: 22px 22px 28px;
  }

  .closingFigure {
    min-height: 0;
  }

  .closingLoop {
    flex: 0 0 auto;
  }

  .closingSplit {
    grid-template-columns: 1fr 1fr;
  }

  body.isClosing {
    padding-bottom: 88px;
  }
}

@media (max-width: 720px) {
  .courseHeader {
    position: relative;
    display: block;
    height: auto;
  }

  .brand {
    height: 58px;
    padding-right: 74px;
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .headerActions {
    position: absolute;
    top: 0;
    right: 0;
    height: 58px;
  }

  .courseMap {
    height: 56px;
  }

  .tocEntry {
    flex-basis: 96px;
  }

  .course {
    display: block;
    min-height: 0;
  }

  .lesson {
    min-height: 0;
    border-right: 0;
    border-bottom: 2px solid var(--ink);
  }

  .lesson h1 {
    font-size: 42px;
  }

  .runtimeHeader {
    align-items: flex-start;
    height: auto;
    min-height: 48px;
    flex-direction: column;
    justify-content: center;
    padding: 8px 12px;
  }

  .runtimeNote {
    display: none;
  }

  .phaseRail {
    height: auto;
    grid-template-columns: repeat(4, 1fr);
  }

  .phase {
    min-height: 0;
    padding: 8px 4px;
    grid-template-columns: 1fr;
    justify-items: center;
    text-align: center;
    border-bottom: 1px solid var(--line);
  }

  .phase > span {
    align-items: center;
  }

  .phase code {
    display: none;
  }

  .runtimeGrid {
    grid-template-rows: minmax(300px, auto) minmax(500px, auto) minmax(240px, auto);
  }

  .memoryPane,
  .codePane,
  .worldPane {
    min-height: 0;
  }

  .cardStack {
    max-height: 520px;
  }

  #codePre {
    min-height: 430px;
    overflow: auto;
  }

  .controls {
    min-height: 70px;
  }

  .controlRow {
    flex-wrap: wrap;
    gap: 8px;
  }

  .hint,
  .speed {
    display: none;
  }

  .stepInd {
    order: 3;
    width: 100%;
    text-align: left;
  }

  .controlRow .primary {
    margin-left: 0;
  }

  .closingPage {
    padding: 20px 16px 28px;
  }

  #closingPanel h2 {
    font-size: 34px;
  }

  .closingLoop li {
    padding: 8px 14px 8px 12px;
  }

  .closingLoop code {
    display: none;
  }

  .closingSplit {
    grid-template-columns: 1fr;
  }

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

  .closingWatched li:nth-child(odd) {
    padding-left: 0;
    border-left: 0;
  }

  .closingWatched li:nth-child(n + 3) {
    padding-top: 12px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}