.fd-topic .gt-nav {
  grid-template-columns: repeat(6, minmax(0, 1fr));
}

.fd-experiment {
  display: grid;
  gap: 18px;
}

.fd-exp-workbench {
  display: grid;
  grid-template-columns: minmax(280px, 360px) minmax(0, 1fr);
  gap: 18px;
  padding-top: 16px;
  border-top: 1px solid rgba(148, 163, 184, 0.24);
}

.fd-exp-story {
  display: grid;
  gap: 12px;
  align-content: start;
  padding: 18px;
  border: 1px solid rgba(20, 184, 166, 0.26);
  border-radius: 16px;
  background: linear-gradient(145deg, #ffffff, #ecfeff);
  box-shadow: 0 16px 34px rgba(15, 118, 110, 0.08);
}

.fd-exp-story > span {
  width: fit-content;
  padding: 5px 10px;
  border-radius: 999px;
  color: #0f766e;
  background: rgba(20, 184, 166, 0.12);
  font-size: 0.78rem;
  font-weight: 950;
}

.fd-exp-story > strong {
  color: #102033;
  font-size: 1.1rem;
  line-height: 1.45;
}

.fd-exp-story p {
  margin: 0;
  color: #536171;
  line-height: 1.65;
}

.fd-exp-board,
.fd-convert-visual,
.fd-reverse-visual,
.fd-case-visual {
  min-height: 220px;
  border: 1px solid rgba(190, 202, 222, 0.82);
  border-radius: 16px;
  padding: 16px;
  background:
    linear-gradient(rgba(255, 255, 255, 0.88), rgba(255, 255, 255, 0.88)),
    repeating-linear-gradient(0deg, rgba(20, 184, 166, 0.055) 0 1px, transparent 1px 28px),
    repeating-linear-gradient(90deg, rgba(245, 158, 11, 0.05) 0 1px, transparent 1px 28px);
  overflow: hidden;
}

.fd-exp-board,
.fd-exp-visual,
.fd-exp-panels,
.fd-lab-board {
  display: grid;
  gap: 12px;
}

.fd-exp-panels,
.fd-lab-board {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.fd-exp-panels section,
.fd-lab-board section {
  display: grid;
  gap: 10px;
  align-content: start;
  padding: 12px;
  border: 1px solid rgba(148, 163, 184, 0.3);
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.94);
}

.fd-exp-panels strong,
.fd-lab-board strong {
  color: #0f172a;
}

.fd-strip {
  display: grid;
  grid-template-columns: repeat(var(--cols), minmax(0, 1fr));
  gap: 4px;
  min-height: 54px;
}

.fd-strip i {
  min-height: 42px;
  border: 1px solid rgba(148, 163, 184, 0.32);
  border-radius: 8px;
  background: #e2e8f0;
}

.fd-strip i.is-on {
  background: #14b8a6;
  border-color: rgba(15, 118, 110, 0.46);
}

.fd-strip.is-result i.is-on {
  background: #f59e0b;
}

.fd-decimal-grid,
.fd-hundred-grid {
  display: grid;
  grid-template-columns: repeat(10, minmax(0, 1fr));
  gap: 3px;
  padding: 8px;
  border-radius: 14px;
  background: #f8fafc;
}

.fd-decimal-grid i,
.fd-hundred-grid i {
  min-height: 12px;
  border-radius: 3px;
  background: #e2e8f0;
}

.fd-decimal-grid i.is-on,
.fd-hundred-grid i.is-on {
  background: #60a5fa;
}

.fd-place-row {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 6px;
}

.fd-place-row section {
  min-height: 64px;
  padding: 8px;
  border-radius: 12px;
  background: #f8fafc;
  text-align: center;
}

.fd-place-row section.is-dot {
  place-items: center;
  background: #e2e8f0;
}

.fd-place-row span {
  color: #64748b;
  font-size: 0.72rem;
  font-weight: 900;
}

.fd-place-row strong,
.fd-place-row b {
  color: #0f172a;
  font-size: 1.5rem;
}

.fd-number-line {
  display: grid;
  padding: 28px 8px 18px;
}

.fd-number-line div {
  position: relative;
  height: 18px;
  border-radius: 999px;
  background: #dbe4f0;
}

.fd-number-line span {
  position: absolute;
  inset-block: 0;
  left: 0;
  border-radius: 999px;
  background: linear-gradient(90deg, #60a5fa, #14b8a6);
}

.fd-number-line i {
  position: absolute;
  top: -34px;
  transform: translateX(-50%);
  padding: 4px 8px;
  border-radius: 999px;
  color: #fff;
  background: #172033;
  font-style: normal;
  font-weight: 950;
  white-space: nowrap;
}

.fd-number-line b {
  position: absolute;
  top: 24px;
  color: #475569;
  font-size: 0.78rem;
}

.fd-number-line .end {
  right: 0;
}

.fd-long-division {
  display: grid;
  gap: 8px;
  padding: 12px;
  border-radius: 14px;
  color: #334155;
  background: #f8fafc;
  line-height: 1.45;
}

.fd-case-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.fd-case {
  display: grid;
  gap: 12px;
  padding: 14px;
  border: 1px solid rgba(190, 202, 222, 0.78);
  border-radius: 16px;
  background: #fff;
}

.fd-case-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 6px 10px;
  align-items: start;
}

.fd-case-head span {
  grid-column: 1 / -1;
  width: fit-content;
  padding: 4px 10px;
  border-radius: 999px;
  color: #0f766e;
  background: rgba(20, 184, 166, 0.12);
  font-size: 0.78rem;
  font-weight: 950;
}

.fd-case-head strong {
  color: #111827;
  font-size: 1.05rem;
}

.fd-case-head em {
  padding: 5px 10px;
  border-radius: 999px;
  color: #fff;
  background: #172033;
  font-style: normal;
  font-size: 0.78rem;
  font-weight: 950;
  white-space: nowrap;
}

.fd-case p {
  margin: 0;
  color: #64748b;
  line-height: 1.55;
  font-size: 0.9rem;
}

.fd-case-controls label {
  display: grid;
  gap: 6px;
  min-width: 0;
  padding: 10px;
  border: 1px solid rgba(190, 202, 222, 0.78);
  border-radius: 12px;
  color: #475569;
  font-size: 0.82rem;
  font-weight: 900;
  background: #f8fafc;
}

.fd-case-controls output,
.fd-case-controls b {
  color: #0f172a;
  font-size: 1rem;
}

.fd-case-visual {
  min-height: 190px;
}

.fd-case-metrics {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.fd-case-metrics span {
  display: grid;
  gap: 4px;
  min-width: 0;
  padding: 9px 10px;
  border-radius: 12px;
  color: #64748b;
  background: #f1f5f9;
  font-size: 0.78rem;
  font-weight: 900;
}

.fd-case-metrics b {
  color: #111827;
  font-size: 0.88rem;
  overflow-wrap: anywhere;
}

.fd-case-result {
  min-height: 82px;
  padding: 12px;
  border-radius: 12px;
  color: #334155;
  font-weight: 850;
  line-height: 1.58;
  background: #f8fafc;
}

.fd-pizza-scene,
.fd-coin-scene,
.fd-ruler-scene,
.fd-cup-scene,
.fd-battery-scene,
.fd-score-scene,
.fd-track-scene,
.fd-chocolate-scene,
.fd-fuel-scene,
.fd-book-scene,
.fd-discount-scene,
.fd-seats-scene {
  display: grid;
  gap: 10px;
  align-items: center;
}

.fd-pizza {
  display: grid;
  place-items: center;
}

.fd-pizza .fd-strip {
  width: 150px;
  min-height: 150px;
  border-radius: 999px;
  overflow: hidden;
  padding: 8px;
  background: #ffedd5;
}

.fd-strip.is-pizza i {
  border-radius: 999px 999px 8px 8px;
  background: #fed7aa;
}

.fd-strip.is-pizza i.is-on {
  background: #fb923c;
}

.fd-pizza-scene strong,
.fd-coin-scene strong,
.fd-ruler-scene strong,
.fd-cup-scene strong,
.fd-battery-scene strong,
.fd-track-scene strong,
.fd-chocolate-scene strong,
.fd-fuel-scene strong,
.fd-book-scene strong,
.fd-discount-scene strong,
.fd-seats-scene strong {
  padding: 8px 10px;
  border-radius: 12px;
  color: #0f172a;
  background: #f1f5f9;
  text-align: center;
}

.fd-coin {
  display: grid;
  place-items: center;
  width: 112px;
  height: 112px;
  margin: 0 auto;
  border: 8px solid #f59e0b;
  border-radius: 999px;
  background: #fef3c7;
  color: #92400e;
}

.fd-coin b {
  font-size: 2rem;
}

.fd-coin span {
  font-weight: 950;
}

.fd-ruler {
  position: relative;
  display: grid;
  grid-template-columns: repeat(11, minmax(0, 1fr));
  min-height: 78px;
  padding-top: 16px;
  border: 3px solid #a16207;
  border-radius: 12px;
  background: #fef3c7;
}

.fd-ruler i {
  border-left: 2px solid #92400e;
  color: #92400e;
  font-style: normal;
  font-size: 0.72rem;
}

.fd-ruler span {
  position: absolute;
  top: 8px;
  bottom: 8px;
  width: 4px;
  transform: translateX(-50%);
  border-radius: 999px;
  background: #ef4444;
}

.fd-cup,
.fd-fuel {
  position: relative;
  width: 86px;
  height: 136px;
  margin: 0 auto;
  border: 4px solid #64748b;
  border-radius: 12px 12px 24px 24px;
  overflow: hidden;
  background: #fff;
}

.fd-cup span,
.fd-fuel span {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  background: #38bdf8;
}

.fd-fuel span {
  background: #22c55e;
}

.fd-cup b,
.fd-fuel b {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-weight: 950;
}

.fd-phone {
  display: grid;
  place-items: center;
  width: 92px;
  height: 150px;
  margin: 0 auto;
  border: 6px solid #111827;
  border-radius: 18px;
  background: #f8fafc;
}

.fd-battery {
  position: relative;
  width: 44px;
  height: 104px;
  border: 4px solid #475569;
  border-radius: 8px;
  overflow: hidden;
}

.fd-battery span {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  background: #22c55e;
}

.fd-battery b {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-size: 0.78rem;
  font-weight: 950;
}

.fd-score-scene {
  grid-template-columns: 96px minmax(0, 1fr);
}

.fd-paper {
  display: grid;
  place-items: center;
  min-height: 118px;
  border: 3px solid #60a5fa;
  border-radius: 12px;
  background: repeating-linear-gradient(0deg, #fff 0 13px, #e0f2fe 13px 15px);
}

.fd-paper b {
  color: #1d4ed8;
  font-size: 1.4rem;
}

.fd-paper span {
  color: #64748b;
  font-size: 0.78rem;
  font-weight: 900;
}

.fd-score-meter {
  position: relative;
  height: 44px;
  border-radius: 999px;
  background: #e2e8f0;
  overflow: hidden;
}

.fd-score-meter span,
.fd-track span {
  position: absolute;
  inset-block: 0;
  left: 0;
  background: linear-gradient(90deg, #60a5fa, #22c55e);
}

.fd-track {
  position: relative;
  min-height: 64px;
  border: 4px solid #475569;
  border-radius: 999px;
  background: #e2e8f0;
}

.fd-track span {
  border-radius: 999px;
}

.fd-track i {
  position: absolute;
  top: 50%;
  width: 24px;
  height: 24px;
  transform: translate(-50%, -50%);
  border: 4px solid #fff;
  border-radius: 999px;
  background: #ef4444;
  box-shadow: 0 4px 10px rgba(15, 23, 42, 0.2);
}

.fd-strip.is-chocolate {
  min-height: 132px;
  padding: 8px;
  border-radius: 14px;
  background: #fef3c7;
}

.fd-strip.is-chocolate i {
  min-height: 26px;
  border-radius: 5px;
  background: #d6b692;
}

.fd-strip.is-chocolate i.is-on {
  background: #7c3f18;
}

.fd-book {
  position: relative;
  width: 92px;
  height: 132px;
  margin: 0 auto;
  border: 4px solid #334155;
  border-radius: 8px 16px 16px 8px;
  background: repeating-linear-gradient(0deg, #fff 0 10px, #e2e8f0 10px 12px);
  overflow: hidden;
}

.fd-book span {
  position: absolute;
  inset-inline: 0;
  bottom: 0;
  background: rgba(96, 165, 250, 0.48);
}

.fd-book b {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-weight: 950;
}

.fd-tag {
  display: grid;
  place-items: center;
  min-height: 92px;
  border: 4px solid #ef4444;
  border-radius: 18px 18px 18px 4px;
  color: #7f1d1d;
  background: #fee2e2;
  font-size: 2.2rem;
  font-weight: 950;
}

.fd-seats {
  display: grid;
  grid-template-columns: repeat(var(--cols), minmax(0, 1fr));
  gap: 4px;
  padding: 8px;
  border-radius: 14px;
  background: #f8fafc;
}

.fd-seats i {
  min-height: 18px;
  border-radius: 6px 6px 12px 12px;
  background: #cbd5e1;
}

.fd-seats i.is-on {
  background: #14b8a6;
}

@media (max-width: 1080px) {
  .fd-case-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 820px) {
  .fd-exp-workbench,
  .fd-exp-panels,
  .fd-lab-board,
  .fd-score-scene {
    grid-template-columns: 1fr;
  }

  .fd-topic .gt-nav,
  .fd-case-grid,
  .fd-case-metrics,
  .fd-place-row {
    grid-template-columns: 1fr;
  }

  .fd-case-head {
    grid-template-columns: 1fr;
  }

  .fd-case-head em {
    width: fit-content;
  }
}