/* CIRA CLASSROOM — Build / Backward Build-up (Unit learning shell remains authoritative).
   Uses global CIRA tokens and the approved shared page geometry. */

.bbu-stage-menu { gap: 2px; }
.bbu-stage-menu__pending {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 8px 13px;
  color: var(--cira-text-muted);
  font-size: 13px;
  font-weight: 750;
  opacity: .6;
  cursor: not-allowed;
  white-space: nowrap;
}

.bbu-help {
  display: flex;
  gap: 15px;
  align-items: center;
  padding: 16px 18px;
  margin-bottom: 18px;
  border: 1px solid #ebdfb9;
  border-radius: var(--cira-radius-panel);
  background: var(--cira-cream);
}
.bbu-help__mark {
  flex: 0 0 auto;
  display: grid;
  place-items: center;
  min-width: 74px;
  min-height: 45px;
  border-radius: 10px;
  background: var(--cira-yellow);
  color: var(--cira-primary);
  font-size: 14px;
  font-weight: 900;
}
.bbu-help p { margin: 0; font-size: 14px; line-height: 1.55; }

.bbu-list { display: grid; gap: 12px; }
.bbu-exercise {
  min-width: 0;
  overflow: hidden;
  border: 1px solid var(--cira-border);
  border-radius: var(--cira-radius-panel);
  background: var(--cira-surface);
  box-shadow: 0 3px 12px rgba(38, 52, 66, .035);
}
.bbu-exercise[open] {
  border-color: #ead38b;
  box-shadow: 0 5px 18px rgba(63, 44, 25, .075);
}
.bbu-exercise > summary {
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) 44px;
  gap: 14px;
  align-items: center;
  min-height: 72px;
  padding: 13px 16px;
  list-style: none;
  cursor: pointer;
  transition: background-color 160ms ease;
}
.bbu-exercise > summary::-webkit-details-marker { display: none; }
.bbu-exercise > summary::marker { content: ""; }
.bbu-exercise > summary:hover,
.bbu-exercise[open] > summary { background: var(--cira-cream); }
.bbu-exercise > summary:focus-visible {
  outline: 3px solid var(--cira-focus);
  outline-offset: -4px;
}
.bbu-exercise__number {
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  color: var(--cira-primary);
  background: var(--cira-yellow);
  font-size: 13px;
  font-weight: 900;
}
.bbu-exercise__sentence {
  color: var(--cira-primary);
  font-size: clamp(15px, 1.7vw, 17px);
  font-weight: 750;
  line-height: 1.48;
  overflow-wrap: break-word;
}
.bbu-exercise__expand {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  justify-self: end;
  border: 1px solid #edcb80;
  border-radius: 10px;
  background: var(--cira-yellow);
  color: var(--cira-primary);
  font-size: 29px;
  font-weight: 450;
  line-height: 1;
}
.bbu-exercise[open] .bbu-exercise__expand { background: var(--cira-red); border-color: var(--cira-red); color: #fff; }
.bbu-exercise__panel {
  padding: 16px 18px 20px;
  border-top: 1px solid var(--cira-border);
  background: #fffefa;
}
.bbu-exercise__toolbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 10px 14px;
  margin: 0 0 15px;
}
.bbu-exercise__hint {
  margin: 0;
  color: var(--cira-text-muted);
  font-size: 13px;
  line-height: 1.4;
}
.bbu-sequence-button {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 14px;
  border: 0;
  border-radius: 9px;
  color: #fff;
  background: var(--cira-red);
  font: inherit;
  font-size: 14px;
  font-weight: 800;
  cursor: pointer;
}
.bbu-sequence-button:hover { background: #a91b28; }
.bbu-sequence-button.is-running { background: var(--cira-primary); }
.bbu-sequence-controls { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.bbu-sequence-stop { background: var(--cira-primary); }
.bbu-sequence-stop[hidden] { display: none; }
.bbu-steps { margin: 0; padding: 0; list-style: none; display: grid; gap: 8px; }
.bbu-step {
  min-width: 0;
  padding: 12px 15px 14px;
  border: 1px solid var(--cira-border);
  border-radius: 10px;
  background: var(--cira-surface);
}
.bbu-step.is-playing { border-color: var(--cira-red); background: #fff7f6; }
.bbu-step.is-waiting { border-color: var(--cira-yellow); background: #fffbeb; }
.bbu-step.is-loading { border-color: #dfc77c; }
.bbu-step__body { min-width: 0; }
.bbu-step__topline {
  display: flex;
  gap: 12px;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}
.bbu-step__role {
  color: var(--cira-primary);
  font-size: 12px;
  font-weight: 850;
  letter-spacing: .07em;
  text-transform: uppercase;
}
.bbu-step__plays {
  color: var(--cira-primary);
  font-size: 13px;
  font-weight: 750;
  white-space: nowrap;
}
.bbu-step__timeline {
  display: grid;
  grid-template-columns: 80px minmax(0, 1fr) 44px;
  align-items: center;
  gap: 14px;
  width: 100%;
}
.bbu-step__time {
  min-width: 0;
  color: var(--cira-text-muted);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  text-align: left;
  white-space: nowrap;
}
.bbu-step__track {
  min-width: 0;
  height: 5px;
  overflow: hidden;
  background: #e9edf1;
  border-radius: 999px;
}
.bbu-step__fill {
  height: 100%;
  width: 0%;
  background: var(--cira-red);
  border-radius: inherit;
}
.bbu-step__play {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--cira-border-strong);
  border-radius: 50%;
  background: var(--cira-surface);
  color: var(--cira-red);
  font: inherit;
  font-size: 18px;
  cursor: pointer;
  justify-self: end;
}
.bbu-step__play:hover { background: var(--cira-cream); }
.bbu-step.is-playing .bbu-step__play,
.bbu-step.is-waiting .bbu-step__play {
  background: var(--cira-red);
  color: #fff;
  border-color: var(--cira-red);
}
/* During a running chunk there is NO Stop/Pause/Skip interaction.
   Disabled controls remain visibly present for layout stability. */
.bbu-step__play:disabled,
.bbu-sequence-button:disabled {
  cursor: not-allowed;
  opacity: .48;
  filter: grayscale(.35);
  pointer-events: none;
}
.is-playback-locked .bbu-exercise > summary {
  cursor: default;
}
.bbu-live-status { min-height: 24px; margin: 14px 2px 0; color: var(--cira-text-muted); font-size: 13px; line-height: 1.5; }

@media (max-width: 767px) {
  .bbu-help { align-items: flex-start; padding: 13px; gap: 10px; }
  .bbu-help__mark { min-width: 54px; min-height: 40px; font-size: 11px; }
  .bbu-exercise > summary { grid-template-columns: 32px minmax(0, 1fr) 44px; gap: 9px; padding: 11px 10px; }
  .bbu-exercise__number { width: 32px; height: 32px; font-size: 12px; }
  .bbu-exercise__panel { padding: 13px 10px 16px; }
  .bbu-step { padding: 11px 9px 12px; }
  .bbu-step__timeline { grid-template-columns: 74px minmax(0, 1fr) 44px; gap: 8px; }
  .bbu-step__role { font-size: 11px; }
  .bbu-step__time { font-size: 11px; }
}