.exam-shell {
  display: none;
  flex: 1;
  flex-direction: column;
  padding: 2rem 1rem 4rem;
}

.exam-shell.active {
  display: flex;
}

.exam-root {
  width: min(var(--content-width), 100%);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.exam-top {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 1.25rem 1.5rem;
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow);
  display: grid;
  gap: 1rem;
}

.exam-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.progress-info {
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}

.progress-label {
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.24em;
  color: var(--muted);
}

.progress-counter {
  font-family: "Space Grotesk", sans-serif;
  font-size: 1.2rem;
  color: var(--text);
}

.progress-counter strong {
  color: var(--violet-soft);
  font-weight: 700;
}

.category-pill {
  padding: 0.5rem 1rem;
  background: linear-gradient(135deg, rgba(154, 107, 255, 0.18), rgba(217, 107, 255, 0.18));
  border: 1px solid var(--violet-glow);
  border-radius: var(--radius-pill);
  font-size: 0.74rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  font-weight: 600;
  color: var(--violet-soft);
}

.progress-row {
  margin: 0;
}

.progress-track {
  width: 100%;
  height: 4px;
  background: rgba(154, 107, 255, 0.12);
  border-radius: var(--radius-pill);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--violet), var(--pink));
  border-radius: var(--radius-pill);
  transition: width 0.4s ease;
}

.timer-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.timer-track {
  flex: 1;
  height: 8px;
  background: rgba(154, 107, 255, 0.1);
  border-radius: var(--radius-pill);
  overflow: hidden;
  position: relative;
}

.timer-fill {
  height: 100%;
  width: 100%;
  background: linear-gradient(90deg, var(--violet-soft), var(--violet));
  border-radius: var(--radius-pill);
  transition: width 0.15s linear;
}

.timer-fill.timer-low {
  background: linear-gradient(90deg, #ffb86b, #ff8a6b);
}

.timer-fill.timer-critical {
  background: linear-gradient(90deg, var(--danger), #ff3a5a);
  animation: timerPulse 0.6s ease-in-out infinite;
}

@keyframes timerPulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

.timer-text {
  font-family: "Space Grotesk", sans-serif;
  font-size: 1rem;
  font-weight: 600;
  color: var(--violet-soft);
  font-variant-numeric: tabular-nums;
  min-width: 60px;
  text-align: right;
}

.exam-stage-wrap {
  position: relative;
}

.exam-stage {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2rem;
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow);
  min-height: 420px;
  display: grid;
  place-items: center;
  position: relative;
  overflow: hidden;
}

.exam-stage::before {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(circle, rgba(154, 107, 255, 0.08), transparent 50%);
  pointer-events: none;
}

.exam-stage.feedback-correct {
  animation: flashCorrect 0.5s ease-out;
}

.exam-stage.feedback-wrong {
  animation: flashWrong 0.5s ease-out;
}

@keyframes flashCorrect {
  0% { box-shadow: var(--shadow), inset 0 0 0 0 rgba(98, 229, 179, 0); }
  40% { box-shadow: var(--shadow), inset 0 0 60px 0 rgba(98, 229, 179, 0.32); }
  100% { box-shadow: var(--shadow), inset 0 0 0 0 rgba(98, 229, 179, 0); }
}

@keyframes flashWrong {
  0% { box-shadow: var(--shadow), inset 0 0 0 0 rgba(255, 106, 134, 0); }
  40% { box-shadow: var(--shadow), inset 0 0 60px 0 rgba(255, 106, 134, 0.32); }
  100% { box-shadow: var(--shadow), inset 0 0 0 0 rgba(255, 106, 134, 0); }
}

.digit-stage,
.switch-stage,
.grid-stage {
  display: none;
  width: 100%;
  position: relative;
  z-index: 1;
}

.digit-stage.active,
.switch-stage.active,
.grid-stage.active {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.5rem;
}

.status-line {
  font-size: 0.85rem;
  color: var(--muted);
  text-align: center;
  min-height: 1.2rem;
}

.status-line.good { color: var(--good); }
.status-line.bad { color: var(--danger); }

.digit-card {
  width: 100%;
  display: flex;
  justify-content: center;
}

.digit-equation {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  align-items: center;
  justify-content: center;
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(1.5rem, 3.5vw, 2.4rem);
  font-weight: 600;
  letter-spacing: 0.02em;
  padding: 1.5rem 1rem;
}

.digit-equation > span {
  color: rgba(220, 210, 245, 0.85);
}

.digit-target {
  color: var(--violet-soft);
  font-weight: 700;
}

.digit-blank {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 3rem;
  height: 3rem;
  padding: 0 0.6rem;
  background: rgba(6, 4, 24, 0.5);
  border: 2px solid var(--line);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: border-color 0.2s ease, background 0.2s ease, transform 0.1s ease;
  font-weight: 700;
  color: var(--violet-soft);
}

.digit-blank:hover {
  border-color: var(--violet);
}

.digit-blank.active {
  border-color: var(--violet);
  background: rgba(154, 107, 255, 0.15);
  box-shadow: 0 0 0 4px rgba(154, 107, 255, 0.2);
}

.digit-pad {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 0.5rem;
  max-width: 480px;
  width: 100%;
}

.digit-key {
  aspect-ratio: 1;
  background: rgba(154, 107, 255, 0.08);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  color: var(--text);
  font-family: "Space Grotesk", sans-serif;
  font-size: 1.25rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease, border-color 0.15s ease;
}

.digit-key:hover:not(:disabled) {
  background: rgba(154, 107, 255, 0.22);
  border-color: var(--violet);
  transform: translateY(-2px);
}

.digit-key:active:not(:disabled) {
  transform: translateY(0);
}

.digit-key.used {
  opacity: 0.25;
  cursor: not-allowed;
}

.digit-actions {
  display: flex;
  gap: 0.75rem;
}

.switch-canvas {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1.2rem;
  width: 100%;
}

.switch-symbol-row {
  display: flex;
  gap: 0.6rem;
  justify-content: center;
  flex-wrap: wrap;
}

.symbol-box {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  background: rgba(6, 4, 24, 0.5);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
}

.symbol-box > div {
  width: 24px;
  height: 24px;
}

.shape-plus {
  position: relative;
}
.shape-plus::before, .shape-plus::after {
  content: "";
  position: absolute;
  background: var(--violet-soft);
}
.shape-plus::before { width: 100%; height: 6px; top: calc(50% - 3px); }
.shape-plus::after { height: 100%; width: 6px; left: calc(50% - 3px); }

.shape-triangle {
  width: 0 !important;
  height: 0 !important;
  border-left: 12px solid transparent;
  border-right: 12px solid transparent;
  border-bottom: 22px solid var(--violet-soft);
}

.shape-square {
  background: var(--violet-soft);
  border-radius: 3px;
}

.shape-circle {
  background: var(--violet-soft);
  border-radius: 50%;
}

.shape-diamond {
  background: var(--violet-soft);
  transform: rotate(45deg);
  width: 18px !important;
  height: 18px !important;
}

.shape-ring {
  background: transparent !important;
  border: 5px solid var(--violet-soft);
  border-radius: 50%;
}

.shape-hex {
  background: var(--violet-soft);
  clip-path: polygon(25% 0, 75% 0, 100% 50%, 75% 100%, 25% 100%, 0 50%);
}

.shape-xmark {
  background: transparent !important;
  position: relative;
}
.shape-xmark::before, .shape-xmark::after {
  content: "";
  position: absolute;
  width: 100%;
  height: 5px;
  background: var(--violet-soft);
  top: calc(50% - 2.5px);
}
.shape-xmark::before { transform: rotate(45deg); }
.shape-xmark::after { transform: rotate(-45deg); }

.shape-star {
  background: var(--violet-soft);
  clip-path: polygon(50% 0%, 61% 35%, 98% 35%, 68% 57%, 79% 91%, 50% 70%, 21% 91%, 32% 57%, 2% 35%, 39% 35%);
}

.tube-stack {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  align-items: stretch;
  padding: 1rem;
  background: rgba(6, 4, 24, 0.4);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  min-width: 320px;
}

#switchRows {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.op-fixed {
  display: flex;
  justify-content: center;
  padding: 0.6rem;
  background: rgba(154, 107, 255, 0.06);
  border-radius: var(--radius-sm);
  font-family: "Space Grotesk", sans-serif;
  color: var(--muted);
  font-size: 0.95rem;
}

.choice-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  justify-content: center;
}

.choice-btn {
  flex: 1;
  min-width: 100px;
  padding: 0.7rem 0.9rem;
  background: rgba(154, 107, 255, 0.1);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: "Space Grotesk", sans-serif;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, transform 0.1s ease;
}

.choice-btn:hover {
  background: rgba(154, 107, 255, 0.22);
  border-color: var(--violet);
  transform: translateY(-1px);
}

.choice-btn.selected {
  background: linear-gradient(135deg, rgba(154, 107, 255, 0.32), rgba(217, 107, 255, 0.32));
  border-color: var(--violet);
  box-shadow: 0 0 0 3px rgba(154, 107, 255, 0.18);
}

.op-stack {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.2rem;
}

.op-expression {
  font-weight: 600;
}

.op-badge,
.choice-badge {
  font-size: 0.62rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

.switch-mask {
  background: rgba(154, 107, 255, 0.15) !important;
  color: var(--violet-soft);
  font-weight: 700;
}

.grid-content {
  display: flex;
  flex-direction: column;
  gap: 1.2rem;
  width: 100%;
  align-items: center;
}

.grid-title {
  font-family: "Space Grotesk", sans-serif;
  font-size: 1.1rem;
  color: var(--violet-soft);
  letter-spacing: 0.04em;
  text-align: center;
}

#gridDynamic {
  width: 100%;
  display: flex;
  justify-content: center;
}

.memory-board {
  position: relative;
  width: min(420px, 100%);
  aspect-ratio: 1;
  background: rgba(6, 4, 24, 0.55);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
}

.hole {
  position: absolute;
  width: 12%;
  height: 12%;
  border-radius: 50%;
  background: rgba(154, 107, 255, 0.08);
  border: 1px solid rgba(154, 107, 255, 0.18);
  transform: translate(-50%, -50%);
  display: grid;
  place-items: center;
  transition: background 0.2s ease, transform 0.2s ease, border-color 0.2s ease;
}

.hole.clickable {
  cursor: pointer;
}

.hole.clickable:hover {
  background: rgba(154, 107, 255, 0.2);
  border-color: var(--violet);
}

.hole.active-memory {
  background: var(--dot-color, var(--violet));
  border-color: var(--dot-color, var(--violet));
  box-shadow: 0 0 16px var(--dot-color, var(--violet-glow));
  transform: translate(-50%, -50%) scale(1.18);
}

.hole.selected-order {
  background: var(--dot-color, var(--violet));
  border-color: var(--dot-color, var(--violet));
}

.hole.selected-order span {
  color: #fff;
  font-weight: 700;
  font-size: 0.8rem;
}

#gridControls {
  display: flex;
  justify-content: center;
  width: 100%;
}

.bottom-controls {
  display: flex;
  gap: 0.75rem;
}

.spatial-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  width: 100%;
}

.spatial-boards {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.mini-board {
  width: 110px;
  height: 110px;
  background: rgba(6, 4, 24, 0.6);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 0.4rem;
}

.operator-sign {
  font-family: "Space Grotesk", sans-serif;
  font-size: 1.5rem;
  color: var(--violet-soft);
  font-weight: 700;
}

.yesno-row {
  display: flex;
  gap: 0.8rem;
}

.yesno-btn {
  padding: 0.85rem 2.2rem;
  background: rgba(154, 107, 255, 0.1);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  color: var(--text);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, transform 0.1s ease;
}

.yesno-btn:hover {
  background: rgba(154, 107, 255, 0.22);
  border-color: var(--violet);
  transform: translateY(-2px);
}

.summary-screen {
  flex: 1;
  display: grid;
  place-items: center;
  padding: 3rem 1rem 5rem;
}

.summary-screen.hidden { display: none; }

.summary-card {
  width: min(640px, 100%);
  padding: 3rem 2.5rem;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(20px);
  box-shadow: var(--shadow);
  text-align: center;
  display: grid;
  gap: 1.3rem;
}

.summary-eyebrow {
  display: inline-block;
  text-transform: uppercase;
  font-size: 0.7rem;
  letter-spacing: 0.28em;
  color: var(--violet-soft);
  padding: 0.4rem 0.9rem;
  border: 1px solid var(--violet-glow);
  border-radius: var(--radius-pill);
  justify-self: center;
}

.summary-heading {
  margin: 0;
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(1.5rem, 4vw, 2rem);
  font-weight: 600;
  color: var(--muted);
}

.index-display {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  padding: 1.5rem 0;
}

.index-value {
  font-family: "Space Grotesk", sans-serif;
  font-size: clamp(5rem, 14vw, 8rem);
  font-weight: 700;
  line-height: 1;
  background: linear-gradient(135deg, #ffffff, var(--violet-soft) 60%, var(--pink));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  letter-spacing: -0.02em;
}

.index-band {
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.28em;
  color: var(--violet-soft);
  font-weight: 600;
}

.index-note {
  margin: 0;
  color: var(--muted);
  font-size: 0.88rem;
  line-height: 1.5;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.6rem;
  padding: 1.2rem 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.summary-metric {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  align-items: center;
}

.summary-metric label {
  font-size: 0.66rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

.summary-metric strong {
  font-family: "Space Grotesk", sans-serif;
  font-size: 1.3rem;
  color: var(--text);
  font-weight: 700;
}

.leaderboard-wrap {
  text-align: left;
  display: grid;
  gap: 0.8rem;
}

.leaderboard-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.leaderboard-header h2 {
  margin: 0;
  font-size: 0.85rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  font-weight: 600;
}

.leaderboard-rank {
  font-size: 0.78rem;
  color: var(--violet-soft);
  letter-spacing: 0.06em;
}

.leaderboard-stack {
  display: grid;
  gap: 0.4rem;
}

.leaderboard-row {
  display: grid;
  grid-template-columns: 2.5rem 1fr auto;
  gap: 0.8rem;
  align-items: center;
  padding: 0.7rem 0.9rem;
  background: rgba(6, 4, 24, 0.45);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
}

.leaderboard-row--current {
  background: linear-gradient(135deg, rgba(154, 107, 255, 0.18), rgba(217, 107, 255, 0.12));
  border-color: var(--violet);
}

.leaderboard-rank-num {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  color: var(--violet-soft);
}

.leaderboard-name {
  font-size: 0.92rem;
  color: var(--text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.leaderboard-index {
  font-family: "Space Grotesk", sans-serif;
  font-weight: 700;
  color: var(--text);
  font-size: 1rem;
}

.action-row {
  display: flex;
  justify-content: center;
  gap: 0.6rem;
}

@media (max-width: 640px) {
  .exam-shell { padding: 1.5rem 0.75rem 3rem; }
  .exam-top { padding: 1rem 1rem; }
  .exam-stage { padding: 1.5rem 1rem; min-height: 380px; }
  .digit-equation { font-size: 1.4rem; }
  .digit-blank { min-width: 2.4rem; height: 2.4rem; }
  .digit-pad { gap: 0.4rem; }
  .symbol-box { width: 36px; height: 36px; }
  .symbol-box > div { width: 18px; height: 18px; }
  .summary-card { padding: 2rem 1.5rem; }
  .summary-grid { grid-template-columns: repeat(2, 1fr); }
  .mini-board { width: 88px; height: 88px; }
}