:root {
  --navy: #2c3e50;
  --teal: #1abc9c;
  --gold: #f1c40f;
  --coral: #e74c3c;
  --slate: #7f8c8d;
  --white: #ffffff;
  --page-bg: #f4f6f8;
  --gray-100: #f7fafc;
  --gray-200: #edf2f7;
  --gray-300: #e2e8f0;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: 'Montserrat', system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial;
  color: var(--navy);
  background: var(--page-bg);
  min-height: 100vh;
  padding-bottom: 80px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ── Header ── */
.page-header {
  padding: 1rem;
  max-width: 1000px;
  margin: 0 auto;
}

.header-grid {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 12px;
  padding: 8px 0;
}

.header-left {
  justify-self: start;
}

.header-right {
  justify-self: end;
  display: flex;
  align-items: center;
  gap: 10px;
}

.page-title {
  margin: 0;
  justify-self: center;
  font-size: clamp(1.25rem, 3vw, 2rem);
  font-weight: 700;
  color: var(--navy);
  letter-spacing: -0.01em;
  text-align: center;
}

.btn--disabled {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
  background: #556366;
  color: var(--white);
}

/* ── Layout ── */
main {
  max-width: 1000px;
  margin: 0 auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.section-card {
  background: var(--white);
  border-radius: 12px;
  padding: 22px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
  min-height: 80px;
}

.section-title {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--slate);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ── Scenario picker ── */
.picker-strip {
  display: flex;
  gap: 12px;
  overflow-x: auto;
  overflow-y: hidden;
  -webkit-overflow-scrolling: touch;
  scroll-snap-type: x proximity;
  padding: 4px 4px 12px;
  margin: 0 -4px;
  scrollbar-width: thin;
  scrollbar-color: var(--gray-300) transparent;
}

.picker-strip::-webkit-scrollbar {
  height: 6px;
}
.picker-strip::-webkit-scrollbar-track {
  background: transparent;
}
.picker-strip::-webkit-scrollbar-thumb {
  background: var(--gray-300);
  border-radius: 3px;
}

.picker-card {
  flex: 0 0 auto;
  width: 130px;
  min-height: 110px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 10px;
  background: var(--white);
  border: 2px solid var(--gray-300);
  border-radius: 10px;
  cursor: pointer;
  font-family: inherit;
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--navy);
  text-align: center;
  line-height: 1.25;
  scroll-snap-align: start;
  transition:
    border-color 0.18s,
    background 0.18s,
    transform 0.18s,
    box-shadow 0.18s;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

.picker-card:hover {
  border-color: var(--slate);
  transform: translateY(-1px);
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.06);
}

.picker-card.active {
  border-color: var(--teal);
  background: rgba(26, 188, 156, 0.1);
  box-shadow: 0 4px 12px rgba(26, 188, 156, 0.18);
}

.picker-card:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 2px;
}

.picker-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 44px;
}

.picker-label {
  font-size: 0.82rem;
  font-weight: 600;
}

/* ── Scenario display panel ── */
.scenario-name {
  margin: 0 0 6px;
  font-size: clamp(1.25rem, 2.6vw, 1.6rem);
  font-weight: 700;
  color: var(--navy);
  line-height: 1.2;
}

.scenario-description {
  margin: 0 0 18px;
  font-size: 0.95rem;
  font-weight: 400;
  color: var(--slate);
  line-height: 1.45;
}

.scenario-canvas-wrap {
  display: flex;
  justify-content: center;
  margin-bottom: 18px;
}

.scenario-canvas {
  width: 100%;
  max-width: 480px;
  height: auto;
  aspect-ratio: 480 / 200;
  background: var(--gray-100);
  border-radius: 10px;
  border: 1.5px solid var(--gray-200);
  display: block;
}

.picker-icon-canvas {
  width: 60px;
  height: 44px;
  display: block;
}

.readouts-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-bottom: 18px;
}

.readout {
  background: var(--gray-100);
  border: 1.5px solid var(--gray-200);
  border-radius: 10px;
  padding: 16px 14px;
  text-align: center;
}

.readout-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--slate);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 8px;
}

.readout-value {
  font-size: clamp(1.6rem, 5.5vw, 2.6rem);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  line-height: 1.05;
  letter-spacing: -0.01em;
}

.readout-value--in {
  color: var(--navy);
}

.readout-value--useful {
  color: var(--teal);
}

.readout-unit {
  font-size: 0.6em;
  font-weight: 600;
  color: var(--slate);
  margin-left: 4px;
}

.display-actions {
  display: flex;
  justify-content: flex-end;
}

/* ── Buttons ── */
.btn {
  display: inline-block;
  padding: 11px 22px;
  border: none;
  border-radius: 6px;
  font-family: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition:
    opacity 0.18s,
    transform 0.18s,
    box-shadow 0.18s;
  white-space: nowrap;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
.btn:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}
.btn:active {
  transform: translateY(0);
}

.gold-btn {
  background: var(--gold);
  color: var(--navy);
  box-shadow: 0 2px 6px rgba(241, 196, 15, 0.35);
}

.teal-btn {
  background: var(--teal);
  color: var(--white);
  box-shadow: 0 2px 6px rgba(26, 188, 156, 0.3);
}

.ghost-btn {
  background: transparent;
  color: var(--slate);
  border: 1.5px solid var(--gray-300);
  font-size: 0.85rem;
  padding: 8px 14px;
  border-radius: 6px;
  font-family: inherit;
  font-weight: 600;
  cursor: pointer;
  transition: border-color 0.18s, background 0.18s;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
.ghost-btn:hover {
  border-color: var(--slate);
  background: var(--gray-100);
}

/* ── Answer panel ── */
.answer-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.answer-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--navy);
}

.answer-input {
  width: 110px;
  padding: 9px 12px;
  border: 2px solid var(--gray-300);
  border-radius: 6px;
  font-family: inherit;
  font-size: 16px;
  font-weight: 600;
  color: var(--navy);
  background: var(--white);
  text-align: center;
  font-variant-numeric: tabular-nums;
  transition: border-color 0.18s;
  -moz-appearance: textfield;
}
.answer-input::-webkit-outer-spin-button,
.answer-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.answer-input:focus {
  outline: none;
  border-color: var(--teal);
}

.feedback {
  display: none;
  font-size: 0.95rem;
  font-weight: 500;
  line-height: 1.5;
  padding: 12px 14px;
  border-radius: 8px;
  border-left: 4px solid var(--gray-300);
  background: var(--gray-100);
  color: var(--navy);
  margin-bottom: 12px;
}
.feedback.visible {
  display: block;
}
.feedback--correct {
  border-left-color: var(--teal);
  background: rgba(26, 188, 156, 0.1);
  color: #16a085;
}
.feedback--amber {
  border-left-color: var(--gold);
  background: rgba(241, 196, 15, 0.12);
  color: #b7950b;
}
.feedback--coral {
  border-left-color: var(--coral);
  background: rgba(231, 76, 60, 0.1);
  color: #c0392b;
}

.answer-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
}

.working-block {
  display: none;
  margin-top: 12px;
  padding: 14px 16px;
  background: var(--gray-100);
  border-radius: 8px;
  border-left: 4px solid var(--navy);
  font-size: 0.95rem;
  line-height: 1.6;
  color: var(--navy);
}
.working-block.visible {
  display: block;
}
.working-block .working-line {
  font-variant-numeric: tabular-nums;
}
.working-block .working-final {
  margin-top: 6px;
  font-weight: 700;
}

/* ── Results table ── */
.results-toolbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 10px;
  margin-bottom: 14px;
}

.results-toolbar .section-title {
  margin-bottom: 0;
}

.results-toolbar-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.results-empty {
  font-size: 0.9rem;
  color: var(--slate);
  text-align: center;
  padding: 28px 14px;
  background: var(--gray-100);
  border-radius: 8px;
  border: 1.5px dashed var(--gray-300);
  font-style: italic;
}

.results-table-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: 8px;
  border: 1px solid var(--gray-200);
}

.results-data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  font-variant-numeric: tabular-nums;
}

.results-data-table thead {
  background: var(--gray-100);
}

.results-data-table th {
  text-align: left;
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--slate);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 10px 12px;
  border-bottom: 2px solid var(--gray-200);
  white-space: nowrap;
}

.results-data-table td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--gray-200);
  color: var(--navy);
  vertical-align: top;
}

.results-data-table tbody tr:last-child td {
  border-bottom: none;
}

.results-data-table tbody tr:hover {
  background: rgba(26, 188, 156, 0.04);
}

.results-data-table .col-num {
  text-align: right;
  white-space: nowrap;
}

.results-data-table .col-pathway {
  color: var(--slate);
  font-size: 0.88rem;
}

.btn--small {
  padding: 8px 14px;
  font-size: 0.85rem;
}

.btn:disabled,
.btn[aria-disabled='true'] {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.navy-btn {
  background: var(--navy);
  color: var(--white);
}

/* ── Guided investigation ── */
#guided-investigation {
  padding: 0;
  overflow: hidden;
}

.guided-toggle {
  display: flex;
  width: 100%;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 22px;
  background: none;
  border: none;
  font-family: inherit;
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--navy);
  text-align: left;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
.guided-toggle:hover {
  background: var(--gray-100);
}
.guided-toggle:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: -2px;
}

.guided-chevron {
  font-size: 1.1rem;
  color: var(--slate);
  transition: transform 0.3s ease;
  display: inline-block;
}

.guided-toggle[aria-expanded='true'] .guided-chevron {
  transform: rotate(180deg);
}

.guided-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
}
.guided-content-inner {
  padding: 0 22px 22px;
}

.guided-list {
  margin: 0;
  padding-left: 22px;
  font-size: 0.95rem;
  line-height: 1.55;
  color: var(--navy);
}
.guided-list li {
  margin-bottom: 12px;
}
.guided-list li:last-child {
  margin-bottom: 0;
}

@media (max-width: 600px) {
  .guided-toggle {
    padding: 18px;
    font-size: 1rem;
  }
  .guided-content-inner {
    padding: 0 18px 18px;
  }
}

/* ── Responsive ── */
@media (max-width: 767px) {
  .header-grid {
    grid-template-columns: 1fr;
    gap: 8px;
    text-align: left;
  }
  .header-left,
  .page-title,
  .header-right {
    justify-self: start;
  }
  .page-title {
    text-align: left;
  }
}

@media (max-width: 600px) {
  main {
    padding: 12px;
    gap: 14px;
  }

  .section-card {
    padding: 18px;
  }

  .readouts-row {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .readout {
    padding: 12px 14px;
  }

  .header-right .btn,
  .header-left .btn {
    font-size: 14px;
    padding: 9px 16px;
  }
}

/* ── Footer ── */
.site-footer {
  background: var(--navy);
  color: var(--white);
  text-align: center;
  padding: 16px;
  font-size: 0.8rem;
  margin-top: 32px;
}

.site-footer p {
  margin: 0;
}