/* styles-learn.css — the Learn overview hero and the module workspace.

   Loaded after styles-ds.css / styles-shell.css; consumes the --ds-* tokens.
   It styles the markup built by ui/learn.js (buildHero) and ui/module.js
   (the .mod-layout workspace) and overrides the older module-reader rules in
   styles-v2.css (the 3-column grid, the heavy "now" rung block, the 3px tone
   border on the card). Rules are scoped under .mod-layout / .learn-hero so
   the Bell Mission, which reuses a few .mod-* classes, keeps its own look.

   Motion: transform/opacity only, 150–300ms, every keyframe fill-mode
   `backwards` so nothing is left on an element once it lands. Reduced motion
   is handled globally (styles-ds.css) plus the explicit blocks at the end. */

/* ---------------------------------------------------------------- tones */
/* One colour per rung of the six-rung ladder, used by the outline rows, the
   rung bar and the stage card alike, so a rung reads the same everywhere. */
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-ground { --tone: var(--ink-3); }
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-bridge { --tone: var(--accent); }
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-name   { --tone: var(--hero-2); }
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-rules  { --tone: var(--warn); }
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-do     { --tone: var(--good); }
:is(.mod-outline-item, .mod-rung, .mod-stage).tone-deep   { --tone: var(--signal); }

/* ============================================================ WORKSPACE */
.mod-layout {
  --mod-side-w: 272px;
  --mod-gap: 32px;
  --mod-sticky-top: calc(var(--shell-topbar-h) + 16px);
  position: relative;
  display: grid;
  grid-template-columns: var(--mod-side-w) minmax(0, 1fr);
  grid-template-areas:
    "head head"
    "side main";
  column-gap: var(--mod-gap);
  row-gap: 22px;
  align-items: start;
  max-width: 1200px;
  margin: 0 auto;
  padding-bottom: 8px;
}
.mod-layout > .mod-head { grid-area: head; }
.mod-layout > .mod-side { grid-area: side; }
.mod-layout > .mod {
  grid-area: main;
  min-width: 0;
  max-width: none;
  width: 100%;
  margin: 0;
  padding: 0;
}

/* ------------------------------------------------------------- header */
.mod-layout .mod-head {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 6px 28px;
  padding: 16px 24px 24px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-1);
  overflow: hidden;
}
/* The faint scientific grid, fading in toward the orbital mark. */
.mod-layout .mod-head::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image: var(--ds-grid);
  background-size: 22px 22px;
  -webkit-mask-image: linear-gradient(90deg, transparent 35%, #000 100%);
  mask-image: linear-gradient(90deg, transparent 35%, #000 100%);
  pointer-events: none;
}
.mod-layout .mod-head > * { position: relative; }

.mod-layout .mod-bar {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: nowrap;
  margin: 0 0 6px;
}
.mod-layout .mod-bar-gap { flex: 1; }
.mod-layout .mod-exit {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  min-height: 32px;
  padding: 4px 12px 4px 6px;
  font-size: 13px;
  font-weight: 600;
  border-radius: var(--ds-radius-1);
}
.mod-layout .mod-exit .ql-icon { transition: transform var(--ds-dur-1) var(--ds-ease); }
.mod-layout .mod-exit:hover .ql-icon { transform: translateX(-2px); }
.mod-layout .mod-mute {
  display: inline-grid;
  place-items: center;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 1px solid transparent;
  border-radius: var(--ds-radius-1);
  color: var(--ink-2);
  opacity: 1;
}
.mod-layout .mod-mute:hover { background: var(--surface-2); border-color: var(--ds-line); color: var(--ink); }
.mod-layout .mod-mute.off { opacity: 1; color: var(--ink-3); }
.mod-layout .mod-mute svg { width: 17px; height: 17px; }

.mod-layout .mod-head-main {
  grid-column: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.mod-layout .mod-title {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 0;
  line-height: 1.2;
}
.mod-layout .mod-n {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px 14px;
  font: 600 11px/1.3 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--accent);
}
.mod-layout .mod-n-ch {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--ink-2);
  letter-spacing: .08em;
}
.mod-layout .mod-n-ch i {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--chapter-hue, var(--accent));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--chapter-hue, var(--accent)) 22%, transparent);
}
.mod-layout .mod-title-h {
  margin: 0;
  font-size: clamp(24px, 2.4vw, 32px);
  line-height: 1.15;
  letter-spacing: -.02em;
  text-wrap: balance;
  overflow-wrap: anywhere;
  color: var(--ink);
}
.mod-layout .mod-title .mod-title-h b { font: inherit; letter-spacing: inherit; }
.mod-layout .mod-head-hook {
  margin: 0;
  max-width: 62ch;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 16.5px;
  line-height: 1.55;
  color: var(--ink-2);
}
.mod-layout .mod-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 16px;
  margin-top: 2px;
  font-size: 13px;
  color: var(--ink-3);
}
.mod-layout .mod-meta-i { display: inline-flex; align-items: center; gap: 6px; font-variant-numeric: tabular-nums; }
.mod-layout .mod-meta-chips { display: inline-flex; flex-wrap: wrap; gap: 6px; }
.mod-layout .mod-chip {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 10px;
  border-radius: var(--ds-radius-pill);
  background: var(--surface-2);
  border: 1px solid var(--ds-line);
  color: var(--ink-2);
  font-size: 12px;
}
/* The one piece of decoration: a quiet orbital, drawn in hairlines. */
.mod-layout .mod-head-orbit {
  grid-column: 2;
  grid-row: 2;
  align-self: center;
  width: 120px;
  height: 120px;
  color: var(--accent);
}
.mod-layout .mod-head-orbit svg { display: block; width: 100%; height: 100%; }
.mod-layout .mod-head-orbit ellipse { stroke: currentColor; stroke-opacity: .24; stroke-width: 1; }
.mod-layout .mod-head-orbit .core { fill: currentColor; fill-opacity: .9; }
.mod-layout .mod-head-orbit .e { fill: var(--signal); }

/* ------------------------------------------------------- side column */
.mod-layout > .mod-side {
  position: sticky;
  top: var(--mod-sticky-top);
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
  max-height: calc(100vh - var(--mod-sticky-top) - 16px);
}
.mod-layout .mod-side-strip:empty { display: none; }
.mod-layout .mod-side-strip { flex: none; min-width: 0; }

/* The outline card — every stage, grouped under its rung. */
.mod-layout .mod-outline {
  position: static;
  top: auto;
  flex: 1 1 auto;
  min-height: 180px;
  max-height: none;
  display: flex;
  flex-direction: column;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-1);
}
.mod-layout .mod-outline-toggle { display: none; }
.mod-layout .mod-outline-panel {
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  min-height: 0;
}
.mod-layout .mod-outline-h {
  display: flex;
  flex-direction: column;
  gap: 3px;
  margin: 0;
  padding: 14px 16px 10px;
  font-family: inherit;
  font-size: inherit;
  letter-spacing: 0;
  text-transform: none;
}
.mod-layout .mod-outline-kicker {
  font: 600 10.5px/1.3 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.mod-layout .mod-outline-title {
  font-size: 14px;
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: -.005em;
  color: var(--ink);
}
.mod-layout .mod-outline-meter {
  display: flex;
  flex-direction: column;
  gap: 7px;
  padding: 0 16px 13px;
  border-bottom: 1px solid var(--ds-line);
}
.mod-layout .mod-outline-meter-t { font-size: 12px; color: var(--ink-3); font-variant-numeric: tabular-nums; }
.mod-layout .mod-outline-meter-bar {
  display: block;
  height: 4px;
  border-radius: var(--ds-radius-pill);
  background: var(--surface-3);
  overflow: hidden;
}
.mod-layout .mod-outline-meter-bar i { display: block; height: 100%; border-radius: inherit; background: var(--ds-accent-grad); }

.mod-layout .mod-outline-list {
  list-style: none;
  flex: 1 1 auto;
  min-height: 0;
  display: flex;
  flex-direction: column;
  flex-wrap: nowrap;
  gap: 4px;
  margin: 0;
  padding: 8px 8px 12px;
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
}
.mod-layout .mod-outline-item { border-radius: 0; overflow: visible; }

/* Rung heading rows. */
.mod-layout .mod-outline-btn {
  display: flex;
  align-items: center;
  gap: 9px;
  width: 100%;
  padding: 8px 8px 5px;
  background: none;
  border: 0;
  border-radius: var(--ds-radius-1);
  font: 600 10.5px/1.2 "IBM Plex Mono", monospace;
  letter-spacing: .1em;
  text-transform: uppercase;
  text-align: left;
  color: var(--ink-3);
  white-space: nowrap;
  cursor: pointer;
}
.mod-layout .mod-outline-btn::after,
.mod-layout .mod-outline-stage-btn:not([aria-current])::after,
.mod-layout .mod-outline-toggle::after { content: none; }
.mod-layout .mod-outline-btn { min-height: 0; }
.mod-layout .mod-outline-btn:hover:not(:disabled) { background: none; color: var(--ink); }
.mod-layout .mod-outline-btn:disabled { opacity: .6; cursor: default; }
.mod-layout .mod-outline-node {
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  border: 1.5px solid var(--tone);
  background: transparent;
}
.mod-layout .mod-outline-rung { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; }
.mod-layout .mod-outline-n { font-size: 10.5px; color: var(--ink-3); opacity: .8; }
.mod-layout .mod-outline-item.mod-outline-active .mod-outline-btn { background: none; color: var(--ink); font-weight: 600; }
.mod-layout .mod-outline-item.mod-outline-done .mod-outline-btn { color: var(--ink-2); }
.mod-layout .mod-outline-item.mod-outline-done .mod-outline-btn::after { content: none; }
.mod-layout .mod-outline-item:is(.mod-outline-done, .mod-outline-active) .mod-outline-node { background: var(--tone); }
.mod-layout .mod-outline-item.mod-outline-active .mod-outline-node {
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--tone) 20%, transparent);
}

/* Stage rows: a numbered node on a thin wire, like qubits on a register. */
.mod-layout .mod-outline-stages { position: relative; list-style: none; margin: 0; padding: 0; }
.mod-layout .mod-outline-stages::before {
  content: "";
  position: absolute;
  left: 17.5px;
  top: 15px;
  bottom: 15px;
  width: 1px;
  background: var(--ds-line-strong);
  pointer-events: none;
}
.mod-layout .mod-outline-item.mod-outline-done .mod-outline-stages::before {
  background: color-mix(in srgb, var(--tone) 50%, transparent);
}
.mod-layout .mod-outline-stage { position: relative; }
.mod-layout .mod-outline-stage-btn {
  position: relative;
  display: grid;
  grid-template-columns: 20px minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 5px 8px;
  background: none;
  border: 0;
  border-radius: var(--ds-radius-1);
  font: 400 13px/1.35 "IBM Plex Sans Condensed", "IBM Plex Sans", system-ui, sans-serif;
  text-align: left;
  letter-spacing: 0;
  text-transform: none;
  min-height: 0;
  color: var(--ink-2);
  cursor: pointer;
  opacity: 1;
}
/* Hover / current wash: a pseudo-element fading in (opacity only). */
.mod-layout .mod-outline-stage-btn::before {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: var(--ds-deck-hover);
  opacity: 0;
  transition: opacity var(--ds-dur-1) var(--ds-ease);
  pointer-events: none;
}
.mod-layout .mod-outline-stage-btn > * { position: relative; }
.mod-layout .mod-outline-stage-btn:hover:not(:disabled)::before { opacity: 1; }
.mod-layout .mod-outline-stage-btn:focus-visible { outline: none; box-shadow: var(--ds-focus); }
.mod-layout .mod-outline-stage-t {
  min-width: 0;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}
.mod-layout .mod-outline-stage-btn > .mod-outline-mark { z-index: 1; }
.mod-layout .mod-outline-mark {
  display: grid;
  place-items: center;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 1px solid var(--ds-line-strong);
  background: var(--surface);
  font: 600 10px/1 "IBM Plex Mono", monospace;
  font-variant-numeric: tabular-nums;
  color: var(--ink-3);
}
.mod-layout .mod-outline-mark svg { width: 12px; height: 12px; }
.mod-layout .mod-outline-stage.is-done .mod-outline-stage-btn { color: var(--ink-2); }
.mod-layout .mod-outline-stage.is-done .mod-outline-mark {
  background: color-mix(in srgb, var(--tone) 14%, var(--surface));
  border-color: color-mix(in srgb, var(--tone) 45%, transparent);
  color: color-mix(in srgb, var(--tone) 80%, var(--ink));
}
/* Current: soft surface + a thin accent rail + precise type. */
.mod-layout .mod-outline-stage.is-current .mod-outline-stage-btn { color: var(--ink); font-weight: 600; }
.mod-layout .mod-outline-stage.is-current .mod-outline-stage-btn::before {
  opacity: 1;
  background: color-mix(in srgb, var(--tone) 10%, transparent);
}
.mod-layout .mod-outline-stage.is-current .mod-outline-stage-btn::after {
  content: "";
  position: absolute;
  left: -8px;
  top: 7px;
  bottom: 7px;
  right: auto;
  width: 2px;
  height: auto;
  border-radius: 2px;
  background: var(--tone);
  transform: none;
  transition: none;
}
.mod-layout .mod-outline-stage.is-current .mod-outline-mark {
  background: var(--tone);
  border-color: var(--tone);
  color: var(--surface);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--tone) 18%, transparent);
}
.mod-layout .mod-outline-stage.is-locked .mod-outline-stage-btn { color: var(--ink-3); cursor: default; }
.mod-layout .mod-outline-stage.is-locked .mod-outline-mark { border-style: dashed; }

/* The circuit trace: current outline row → stage card. */
.mod-layout .mod-trace,
.mod-layout .mod-trace-end {
  position: absolute;
  z-index: 1;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--ds-dur-2) var(--ds-ease);
}
.mod-layout.has-trace .mod-trace,
.mod-layout.has-trace .mod-trace-end { opacity: 1; }
.mod-layout .mod-trace-svg { display: block; overflow: visible; }
.mod-layout .mod-trace-path {
  fill: none;
  stroke: color-mix(in srgb, var(--accent) 50%, transparent);
  stroke-width: 1.25;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.mod-layout .mod-trace-end {
  width: 7px;
  height: 7px;
  margin: -3.5px 0 0 -3.5px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 18%, transparent);
}
.mod-layout.mod-is-done .mod-trace,
.mod-layout.mod-is-done .mod-trace-end { opacity: 0; }

/* The side tutor (the old in-module panel). */
.mod-layout .mod-tutor-panel {
  position: static;
  flex: none;
  max-height: none;
  margin: 0;
  padding: 0;
  border: 0;
  overflow: visible;
}
.mod-layout .mod-tutor-toggle {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 9px;
  width: 100%;
  min-height: 42px;
  padding: 8px 14px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-2);
  color: var(--ink-2);
  font-size: 13px;
  font-weight: 600;
}
.mod-layout .mod-tutor-toggle:hover { border-color: var(--ds-line-strong); color: var(--ink); }
.mod-layout .mod-tutor-toggle.mod-tutor-open {
  background: var(--surface);
  border-color: color-mix(in srgb, var(--accent) 40%, var(--ds-line));
  color: var(--ink);
}
.mod-layout .mod-tutor-toggle > .ql-icon:first-child { color: var(--accent); }
.mod-layout .mod-tutor-toggle .mod-tutor-chev { margin-left: auto; transition: transform var(--ds-dur-2) var(--ds-ease); }
.mod-layout .mod-tutor-toggle.mod-tutor-open .mod-tutor-chev { transform: rotate(180deg); }
.mod-layout .mod-tutor-body {
  margin-top: 8px;
  padding: 12px 14px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-2);
  font-size: 13.5px;
  line-height: 1.55;
  animation: ql-learn-rise var(--ds-dur-2) var(--ds-ease-out) backwards;
}

/* --------------------------------------------------- reading column */
.mod-layout .mod-progress-sec {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 0 0 14px;
}
.mod-layout .mod-progress-top {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 14px;
  min-width: 0;
}
.mod-layout .mod-mascot-row { flex: none; margin: 0; }
.mod-layout .mod-where {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 4px 9px;
  margin-right: auto;
  min-width: 0;
}
.mod-layout .mod-where-k {
  font: 600 10.5px/1 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.mod-layout .mod-where .mod-count { font-size: 15px; font-weight: 600; color: var(--ink); }
.mod-layout .mod-where-pct { font-size: 12.5px; color: var(--ink-3); }
.mod-layout .mod-completion-chip { font-size: 11.5px; padding: 4px 11px; border-radius: var(--ds-radius-pill); }

/* The rung ladder: one segmented bar, each segment as wide as its rung. */
.mod-layout .mod-ladder {
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 0;
  overflow: visible;
}
.mod-layout .mod-rung {
  flex: var(--seg, 1) 1 0%;
  min-width: 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 6px;
  padding: 4px 0 2px;
  background: none;
  border: 0;
  border-radius: 4px;
  font: 600 10px/1.2 "IBM Plex Mono", monospace;
  letter-spacing: .08em;
  text-transform: uppercase;
  text-align: left;
  color: var(--ink-3);
  cursor: pointer;
}
.mod-layout .mod-rung > span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.mod-layout .mod-rung:disabled { opacity: .55; cursor: default; }
.mod-layout .mod-rung.done { color: var(--ink-2); border: 0; }
.mod-layout .mod-rung.now { background: none; border: 0; color: var(--ink); font-weight: 600; }
.mod-layout .mod-rung:hover:not(:disabled) { color: var(--ink); }
.mod-layout .mod-rung:focus-visible { outline: none; box-shadow: var(--ds-focus); }
.mod-layout .mod-rung-bar {
  position: relative;
  display: block;
  height: 6px;
  border-radius: var(--ds-radius-pill);
  background: color-mix(in srgb, var(--tone) 16%, var(--surface-3));
  overflow: hidden;
}
.mod-layout .mod-rung-bar::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: var(--tone);
  transform-origin: left center;
  transform: scaleX(var(--fill, 0));
}
.mod-layout .mod-rung.now .mod-rung-bar {
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--tone) 14%, transparent);
}

/* The stage card. */
.mod-layout .mod-stage {
  position: relative;
  padding: 26px 32px 30px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-top: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-2);
}
/* A thin tone accent across the top edge — the rung, at a glance. */
.mod-layout .mod-stage::before {
  content: "";
  position: absolute;
  left: 24px;
  right: 24px;
  top: -1px;
  height: 2px;
  border-radius: 0 0 2px 2px;
  background: var(--tone, var(--accent));
  pointer-events: none;
}
.mod-layout .mod-rung-label {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px 10px;
  margin: 0 0 10px;
}
.mod-layout .mod-rung-node {
  flex: none;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--tone);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--tone) 18%, transparent);
}
.mod-layout .mod-rung-label b { color: color-mix(in srgb, var(--tone) 75%, var(--ink)); }
.mod-layout .mod-rung-label .mod-rung-note { font-size: 12.5px; color: var(--ink-3); }
.mod-layout .mod-stage-kind {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  margin-left: auto;
  padding: 3px 10px 3px 8px;
  border-radius: var(--ds-radius-pill);
  background: var(--surface-2);
  border: 1px solid var(--ds-line);
  font-size: 11.5px;
  font-weight: 600;
  color: var(--ink-2);
}
.mod-layout .mod-rung-label .mod-stage-kind span { font-size: inherit; color: inherit; }
.mod-layout .mod-stage .mod-h { text-wrap: balance; }

/* Stage change — direction of travel; `backwards` fill only. A stage that
   has borrowed the real workbench gets opacity only (module.js decides). */
.mod-layout .mod-stage.mod-stage-in-fwd  { animation: ql-mod-in-fwd var(--ds-dur-3) var(--ds-ease-out) backwards; }
.mod-layout .mod-stage.mod-stage-in-back { animation: ql-mod-in-back var(--ds-dur-3) var(--ds-ease-out) backwards; }
.mod-layout .mod-stage.mod-stage-fade    { animation: ql-learn-fade var(--ds-dur-2) var(--ds-ease) backwards; }

/* Controls: progress line, Back · what's next · the one primary action. */
.mod-layout .mod-controls {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  grid-template-areas:
    "prog prog prog"
    "back up next";
  align-items: center;
  gap: 12px 18px;
  margin-top: 14px;
  padding: 14px 16px 14px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-1);
}
.mod-layout .mod-controls > .mod-progress-wrap { grid-area: prog; }
.mod-layout .mod-controls > .mod-back { grid-area: back; }
.mod-layout .mod-controls > .mod-upnext { grid-area: up; }
.mod-layout .mod-controls > .mod-next { grid-area: next; }
.mod-layout .mod-progress { height: 5px; background: var(--surface-3); border-radius: var(--ds-radius-pill); }
.mod-layout .mod-progress i { border-radius: inherit; background: var(--ds-accent-grad); }
.mod-layout .mod-back,
.mod-layout .mod-next {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  min-height: 40px;
}
.mod-layout .mod-back { padding: 8px 14px 8px 10px; }
.mod-layout .mod-next { padding: 8px 16px 8px 18px; font-weight: 600; }
.mod-layout .mod-back .ql-icon,
.mod-layout .mod-next .ql-icon { transition: transform var(--ds-dur-1) var(--ds-ease); }
.mod-layout .mod-back:hover:not(:disabled) .ql-icon { transform: translateX(-2px); }
.mod-layout .mod-next:hover:not(:disabled) .ql-icon { transform: translateX(2px); }
.mod-layout .mod-upnext {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
}
.mod-layout .mod-upnext-k {
  font: 600 10px/1.2 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.mod-layout .mod-upnext-t {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
/* Only while Continue is actually locked. */
.mod-layout .mod-upnext-lock {
  display: none;
  align-items: center;
  gap: 5px;
  font-size: 12px;
  color: color-mix(in srgb, var(--warn) 80%, var(--ink));
}
.mod-layout .mod-controls:has(.mod-next:disabled) .mod-upnext-lock { display: inline-flex; }

/* ---------------------------------------------------- responsive */
@media (max-width: 1280px) {
  .mod-layout { --mod-side-w: 244px; --mod-gap: 26px; }
  .mod-layout .mod-stage { padding: 24px 26px 28px; }
}

/* Single column: the side dissolves (display:contents) — the outline becomes
   a compact sticky stage bar above the stage; station and tutor drop below. */
@media (max-width: 900px) {
  .mod-layout {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    gap: 14px;
  }
  .mod-layout > .mod-head { order: 0; }
  .mod-layout > .mod-side { display: contents; }
  .mod-layout > .mod { order: 2; }
  .mod-layout .mod-side-strip { order: 3; }
  .mod-layout .mod-tutor-panel { order: 4; }
  .mod-layout .mod-trace,
  .mod-layout .mod-trace-end { display: none; }

  .mod-layout .mod-outline {
    order: 1;
    position: sticky;
    top: calc(var(--shell-topbar-h) + 8px);
    z-index: 6;
    flex: none;
    min-height: 0;
    overflow: visible;
    border-radius: var(--ds-radius-2);
    box-shadow: var(--ds-shadow-2);
  }
  .mod-layout .mod-outline-toggle {
    display: flex;
    align-items: center;
    gap: 10px;
    width: 100%;
    min-height: 48px;
    padding: 6px 14px;
    background: none;
    border: 0;
    border-radius: inherit;
    font: inherit;
    letter-spacing: 0;
    text-transform: none;
    text-align: left;
    color: var(--ink);
    cursor: pointer;
  }
  .mod-layout .mod-outline-toggle > .ql-icon:first-child { color: var(--accent); flex: none; }
  .mod-layout .mod-outline-toggle:focus-visible { outline: none; box-shadow: var(--ds-focus); }
  .mod-layout .mod-outline-toggle-t {
    flex: 1;
    min-width: 0;
    display: flex;
    align-items: baseline;
    gap: 8px;
    overflow: hidden;
    white-space: nowrap;
  }
  .mod-layout .mod-outline-toggle-t b { font-size: 14px; font-weight: 600; font-variant-numeric: tabular-nums; }
  .mod-layout .mod-outline-toggle-t span {
    font: 600 10.5px/1 "IBM Plex Mono", monospace;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--ink-3);
    overflow: hidden;
    text-overflow: ellipsis;
  }
  .mod-layout .mod-outline-toggle-hint { flex: none; font-size: 12px; color: var(--ink-3); }
  .mod-layout .mod-outline-chev { flex: none; color: var(--ink-3); transition: transform var(--ds-dur-2) var(--ds-ease); }
  .mod-layout .mod-outline.is-open .mod-outline-chev { transform: rotate(180deg); }

  .mod-layout .mod-outline-panel { display: none; }
  .mod-layout .mod-outline.is-open .mod-outline-panel {
    display: flex;
    position: absolute;
    left: 0;
    right: 0;
    top: calc(100% + 6px);
    max-height: min(460px, calc(100vh - var(--shell-topbar-h) - var(--shell-bottomnav-h) - 96px));
    background: var(--surface);
    border: 1px solid var(--ds-line);
    border-radius: var(--ds-radius-2);
    box-shadow: var(--ds-shadow-pop);
    overflow: hidden;
    animation: ql-learn-drop var(--ds-dur-2) var(--ds-ease-out) backwards;
  }
  .mod-layout .mod-head-orbit { width: 88px; height: 88px; }
}

@media (max-width: 640px) {
  .mod-layout .mod-head { grid-template-columns: minmax(0, 1fr); padding: 12px 16px 18px; }
  .mod-layout .mod-head-orbit { display: none; }
  .mod-layout .mod-title-h { font-size: 23px; }
  .mod-layout .mod-head-hook { font-size: 15.5px; }
  .mod-layout .mod-stage { padding: 20px 16px 22px; }
  .mod-layout .mod-stage::before { left: 16px; right: 16px; }
  .mod-layout .mod-rung-note { display: none; }
  .mod-layout .mod-controls {
    grid-template-columns: auto minmax(0, 1fr);
    grid-template-areas:
      "prog prog"
      "up   up"
      "back next";
    gap: 10px 10px;
    padding: 12px;
  }
  .mod-layout .mod-controls > .mod-next { width: 100%; }
  .mod-layout .mod-ladder { gap: 3px; }
  .mod-layout .mod-rung { font-size: 9px; letter-spacing: .04em; }
}

/* ============================================================ LEARN HERO */
.lessons > .learn-hero { grid-column: 1 / -1; }
.learn-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(280px, 1fr);
  gap: 16px;
  margin: 4px 0 26px;
}

/* The module you should open next — the page's one primary action. */
.learn-now {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-width: 0;
  padding: 22px 24px 20px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-2);
  overflow: hidden;
}
/* Chapter-hue rail on the left edge + a faint grid in the corner. */
.learn-now::before {
  content: "";
  position: absolute;
  left: 0;
  top: 18px;
  bottom: 18px;
  width: 3px;
  border-radius: 0 3px 3px 0;
  background: var(--chapter-hue, var(--accent));
}
.learn-now::after {
  content: "";
  position: absolute;
  right: 0;
  top: 0;
  width: 46%;
  height: 100%;
  background-image: var(--ds-grid);
  background-size: 22px 22px;
  -webkit-mask-image: radial-gradient(120% 90% at 100% 0%, #000 0%, transparent 70%);
  mask-image: radial-gradient(120% 90% at 100% 0%, #000 0%, transparent 70%);
  pointer-events: none;
}
.learn-now > * { position: relative; z-index: 1; }
.learn-now-k {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  font: 600 11px/1.3 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--accent);
}
.learn-now.is-done .learn-now-k { color: var(--good); }
.learn-now-ch {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 4px 14px;
  font-size: 12.5px;
  color: var(--ink-3);
}
.learn-now-ch .mono { font-size: 11.5px; letter-spacing: .08em; text-transform: uppercase; color: var(--ink-2); }
.learn-now-chn { display: inline-flex; align-items: center; gap: 7px; }
.learn-now-chn i,
.learn-map-cap i {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--chapter-hue, var(--accent));
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--chapter-hue, var(--accent)) 22%, transparent);
  flex: none;
}
.learn-now-title {
  margin: 0;
  font-size: clamp(22px, 2.2vw, 28px);
  line-height: 1.18;
  font-weight: 700;
  letter-spacing: -.02em;
  text-wrap: balance;
  overflow-wrap: anywhere;
  color: var(--ink);
}
.learn-now-hook {
  margin: 0;
  max-width: 60ch;
  font-family: "Source Serif 4", Georgia, serif;
  font-size: 16px;
  line-height: 1.55;
  color: var(--ink-2);
}
.learn-now-prog { display: flex; flex-direction: column; gap: 7px; max-width: 460px; margin-top: 2px; }
.learn-now-prog-t { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; font-size: 13px; }
.learn-now-prog-t b { font-weight: 600; color: var(--ink); font-variant-numeric: tabular-nums; }
.learn-now-prog-t .mono { font-size: 11.5px; color: var(--ink-3); }
.learn-now-bar {
  height: 6px;
  border-radius: var(--ds-radius-pill);
  background: color-mix(in srgb, var(--chapter-hue, var(--accent)) 14%, var(--surface-3));
  overflow: hidden;
}
.learn-now-bar i { display: block; height: 100%; border-radius: inherit; background: var(--chapter-hue, var(--accent)); }
.learn-now-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 16px;
  font-size: 13px;
  color: var(--ink-3);
}
.learn-meta-i { display: inline-flex; align-items: center; gap: 6px; font-variant-numeric: tabular-nums; }
.learn-chip {
  display: inline-flex;
  align-items: center;
  min-height: 24px;
  padding: 2px 10px;
  border-radius: var(--ds-radius-pill);
  background: var(--surface-2);
  border: 1px solid var(--ds-line);
  font-size: 12px;
  color: var(--ink-2);
}
.learn-now-acts { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-top: 6px; }
.learn-now-go,
.learn-now-more { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 42px; }
.learn-now-go { padding: 9px 18px 9px 20px; font-weight: 600; }
.learn-now-go .ql-icon { transition: transform var(--ds-dur-1) var(--ds-ease); }
.learn-now-go:hover .ql-icon { transform: translateX(3px); }
.learn-now-then {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 2px 10px;
  margin-top: 6px;
  padding-top: 12px;
  border-top: 1px solid var(--ds-line);
  font-size: 13px;
  color: var(--ink-2);
}
.learn-now-then-k {
  font: 600 10px/1.2 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.learn-now-then-t { font-weight: 600; color: var(--ink); }
.learn-now-then-r { flex-basis: 100%; font-size: 12.5px; color: var(--ink-3); }

/* The whole course at a glance. */
.learn-overall {
  display: flex;
  flex-direction: column;
  gap: 12px;
  min-width: 0;
  padding: 20px 20px 18px;
  background: var(--surface);
  border: 1px solid var(--ds-line);
  border-radius: var(--ds-radius-3);
  box-shadow: var(--ds-shadow-1);
}
.learn-overall-k {
  font: 600 11px/1.3 "IBM Plex Mono", monospace;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--ink-3);
}
.learn-overall-big { display: flex; align-items: baseline; flex-wrap: wrap; gap: 4px 8px; color: var(--ink-2); font-size: 13.5px; }
.learn-overall-big b { font-size: 34px; line-height: 1; font-weight: 600; color: var(--ink); letter-spacing: -.02em; }
.learn-overall-pct {
  margin-left: auto;
  padding: 2px 9px;
  border-radius: var(--ds-radius-pill);
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
}
/* One segment per chapter, as wide as the chapter, filled as far as done. */
.learn-map { display: flex; gap: 3px; height: 10px; }
.learn-map-seg {
  position: relative;
  flex-basis: 0;
  min-width: 6px;
  border-radius: 3px;
  background: color-mix(in srgb, var(--chapter-hue) 16%, var(--surface-3));
  overflow: hidden;
}
.learn-map-seg i { position: absolute; left: 0; top: 0; bottom: 0; display: block; background: var(--chapter-hue); }
.learn-map-seg.is-here { box-shadow: 0 0 0 2px var(--surface), 0 0 0 3.5px color-mix(in srgb, var(--chapter-hue) 70%, transparent); }
.learn-map-cap {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--ink-2);
}
.learn-map-cap .mono { margin-left: auto; font-size: 12px; color: var(--ink-3); }
.learn-stats {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 2px 0 0;
  padding: 12px 0 0;
  border-top: 1px solid var(--ds-line);
}
.learn-stats li {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 4px 8px;
  font-size: 13px;
  color: var(--ink-2);
}
.learn-stats li > .ql-icon { color: var(--accent); flex: none; }
.learn-stats b { font-weight: 600; color: var(--ink); }
.learn-stats .mono { font-size: 12px; color: var(--ink-3); }
.learn-stats-bar {
  flex-basis: 100%;
  height: 4px;
  margin-left: 24px;
  border-radius: var(--ds-radius-pill);
  background: var(--surface-3);
  overflow: hidden;
}
.learn-stats-bar i { display: block; height: 100%; border-radius: inherit; background: var(--ds-accent-grad); }

@media (max-width: 1100px) {
  .learn-hero { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  .learn-hero { gap: 12px; margin-bottom: 20px; }
  .learn-now { padding: 18px 16px 16px; }
  .learn-overall { padding: 16px; }
  .learn-now-acts > .btn { flex: 1 1 auto; }
}

/* ============================================================ KEYFRAMES */
@keyframes ql-mod-in-fwd  { from { opacity: 0; transform: translate3d(14px, 0, 0); } }
@keyframes ql-mod-in-back { from { opacity: 0; transform: translate3d(-14px, 0, 0); } }
@keyframes ql-learn-fade  { from { opacity: 0; } }
@keyframes ql-learn-rise  { from { opacity: 0; transform: translate3d(0, 4px, 0); } }
@keyframes ql-learn-drop  { from { opacity: 0; transform: translate3d(0, -6px, 0); } }

@media (prefers-reduced-motion: reduce) {
  .mod-layout .mod-stage,
  .mod-layout .mod-tutor-body,
  .mod-layout .mod-outline.is-open .mod-outline-panel { animation: none; }
  .mod-layout .mod-trace,
  .mod-layout .mod-trace-end { transition: none; }
}
:root[data-reduced-motion="true"] .mod-layout .mod-stage,
:root[data-reduced-motion="true"] .mod-layout .mod-tutor-body,
:root[data-reduced-motion="true"] .mod-layout .mod-outline.is-open .mod-outline-panel { animation: none; }