:root {
  --tab-bar-height: 4rem;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  min-height: 100vh;
  font-family: var(--font-display);
  color: var(--ink);
  background: var(--paper);
  font-variant-numeric: tabular-nums;
  padding: 0;
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

.app {
  width: 100%;
  max-width: 60rem;
  margin: 0 auto;
  padding: 1rem 1rem calc(var(--tab-bar-height) + 1.5rem);
  flex: 1;
}

.screens {
  width: 100%;
}

.screen {
  background: var(--panel);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  padding: 2rem 1.75rem;
  min-height: 28rem;
}

.hidden {
  display: none !important;
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(1.75rem, 2.5vw + 1rem, 2.25rem);
  font-weight: 800;
  color: var(--ink-strong);
  margin: 0 auto 0.75rem;
  letter-spacing: -0.015em;
  text-align: center;
  position: relative;
  display: block;
  padding-bottom: 0.5rem;
}

h1::after {
  content: "";
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  bottom: 0;
  width: 3.5rem;
  height: 3px;
  background: var(--coral);
  border-radius: 2px;
}

h2 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 2vw + 0.75rem, 2rem);
  font-weight: 800;
  color: var(--ink-strong);
  margin: 0 0 0.75rem;
  text-align: center;
}

.subtle {
  color: var(--ink-soft);
  text-align: center;
  margin: 0 0 1.5rem;
}

.muted {
  color: var(--ink-faint);
  text-align: center;
}

.prose {
  max-width: 38rem;
  margin: 0 auto;
  color: var(--ink);
  line-height: 1.6;
}

.prose p {
  margin: 0 0 1rem;
}

.prose ul {
  padding-left: 1.25rem;
}

.prose li {
  margin-bottom: 0.5rem;
}

/* -- Buttons -- */

.primary {
  font: inherit;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.9rem 1.9rem;
  border-radius: var(--radius-md);
  border: 2px solid var(--ink);
  background: var(--accent);
  color: var(--ink);
  cursor: pointer;
  transition:
    background-color 120ms ease,
    transform 80ms ease,
    opacity 120ms ease;
}

.primary:hover:not(:disabled) {
  background: var(--accent-dark);
}

.primary:active:not(:disabled) {
  transform: scale(0.97);
}

.primary:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.primary:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: 3px;
}

.secondary {
  font: inherit;
  font-family: var(--font-display);
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.9rem 1.9rem;
  border-radius: var(--radius-md);
  border: 2px solid var(--ink);
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  transition:
    background-color 120ms ease,
    transform 80ms ease;
}

.secondary:hover {
  background: var(--accent-soft);
}

.secondary:active {
  transform: scale(0.97);
}

.secondary:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: 3px;
}

.danger {
  font: inherit;
  font-family: var(--font-display);
  font-size: 0.875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  border: 2px solid var(--coral-dark);
  background: transparent;
  color: var(--coral-dark);
  cursor: pointer;
  transition:
    background-color 120ms ease,
    color 120ms ease,
    transform 80ms ease;
}

.danger:hover {
  background: var(--coral-soft);
}

.danger:active {
  transform: scale(0.97);
}

/* -- Settings -- */

.setup-group {
  border: none;
  margin: 0 auto 1.25rem;
  padding: 0;
  max-width: 30rem;
  text-align: center;
}

.setup-group legend {
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-soft);
  margin-bottom: 0.5rem;
}

.check-row {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.6rem 1rem;
  background: var(--panel-muted);
  border-radius: var(--radius-md);
  border: 2px solid var(--edge);
  cursor: pointer;
  user-select: none;
}

.check-row input[type="checkbox"] {
  width: 1.1rem;
  height: 1.1rem;
  accent-color: var(--coral);
}

.segmented {
  display: inline-flex;
  gap: 0.25rem;
  padding: 0.3rem;
  background: var(--panel-muted);
  border-radius: var(--radius-md);
  border: 2px solid var(--edge);
}

.segmented input {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.segmented label {
  font-family: var(--font-display);
  padding: 0.55rem 1.1rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-soft);
  cursor: pointer;
  transition: background-color 120ms ease, color 120ms ease;
  user-select: none;
}

.segmented input:checked + label {
  background: var(--accent);
  color: var(--ink);
  box-shadow: var(--shadow-sm);
}

.segmented input:focus-visible + label {
  outline: 3px solid var(--coral);
  outline-offset: 3px;
}

.factor-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.5rem;
  max-width: 24rem;
  margin: 0 auto;
}

.factor-btn {
  font: inherit;
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 800;
  padding: 0.75rem 0;
  border: 2px solid var(--edge);
  border-radius: var(--radius-md);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  transition:
    background-color 120ms ease,
    border-color 120ms ease,
    color 120ms ease,
    transform 80ms ease;
}

.factor-btn:hover {
  background: var(--panel-muted);
  border-color: var(--edge-strong);
}

.factor-btn:active {
  transform: scale(0.95);
}

.factor-btn.active {
  background: var(--coral);
  border-color: var(--coral-dark);
  color: #ffffff;
}

.factor-btn:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: 2px;
}

#start-game-btn {
  display: block;
  margin: 2rem auto 0.5rem;
}

/* -- Players -- */

.players-list {
  list-style: none;
  padding: 0;
  margin: 0 auto 1.5rem;
  max-width: 32rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.player-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  background: var(--panel-muted);
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  flex-wrap: wrap;
}

.player-row.active {
  background: var(--coral-soft);
  border-color: var(--coral);
}

.player-row-name {
  font-family: var(--font-display);
  font-weight: 700;
  color: var(--ink);
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.player-row-badge {
  font-family: var(--font-display);
  font-size: 0.7rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: 0.25rem 0.6rem;
  background: var(--coral);
  color: #ffffff;
  border-radius: var(--radius-sm);
}

.player-row-actions {
  display: flex;
  gap: 0.5rem;
}

.player-row-actions button {
  font: inherit;
  font-family: var(--font-display);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  border: 2px solid transparent;
  background: transparent;
  transition: background-color 120ms ease, color 120ms ease;
}

.player-row-actions .btn-set {
  color: var(--ink);
  border-color: var(--ink);
}

.player-row-actions .btn-set:hover {
  background: var(--accent-soft);
}

.player-row-actions .btn-delete {
  color: var(--coral-dark);
  border-color: var(--coral-dark);
}

.player-row-actions .btn-delete:hover {
  background: var(--coral-soft);
}

.add-player-form {
  display: flex;
  gap: 0.5rem;
  max-width: 32rem;
  margin: 0 auto;
}

.add-player-form input[type="text"] {
  flex: 1;
  font: inherit;
  font-family: var(--font-display);
  font-size: 1rem;
  padding: 0.75rem 1rem;
  border: 2px solid var(--edge);
  border-radius: var(--radius-md);
  background: var(--panel);
  color: var(--ink);
}

.add-player-form input[type="text"]:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: 2px;
  border-color: var(--coral);
}

/* -- Progress -- */

.user-cycler {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.cycle-btn {
  font: inherit;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.55rem 1.1rem;
  border: 2px solid var(--ink);
  border-radius: var(--radius-md);
  background: transparent;
  color: var(--ink);
  cursor: pointer;
  transition: background-color 120ms ease;
}

.cycle-btn:hover {
  background: var(--accent-soft);
}

.user-cycler-name {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--ink-strong);
  min-width: 10rem;
  text-align: center;
}

.progress-table {
  width: 100%;
  max-width: 42rem;
  margin: 0 auto 1.25rem;
  border-collapse: collapse;
  font-family: var(--font-display);
  font-size: 1rem;
}

.progress-table th,
.progress-table td {
  padding: 0.75rem 0.75rem;
  text-align: left;
  border-bottom: 1px solid var(--edge);
}

.progress-table th {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-soft);
  background: var(--panel-muted);
}

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

.progress-table td:nth-child(3),
.progress-table td:nth-child(4) {
  font-weight: 700;
  text-align: right;
}

#clear-progress-btn {
  display: block;
  margin: 0 auto;
}

/* -- Game screens -- */

.game-screen {
  padding: 1.5rem 1.25rem;
}

.game-header-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.75rem;
  margin-bottom: 1rem;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  flex-wrap: wrap;
}

.game-player {
  font-weight: 800;
  color: var(--ink-strong);
}

.game-progress {
  font-weight: 700;
}

.game-score {
  font-weight: 800;
  color: var(--coral-dark);
}

.equation {
  font-family: var(--font-display);
  font-size: clamp(1.75rem, 3vw + 1rem, 2.5rem);
  font-weight: 800;
  text-align: center;
  margin: 1rem 0 1rem;
  letter-spacing: -0.01em;
  color: var(--ink-strong);
  font-variant-numeric: tabular-nums;
}

/* Apples grid */

.apples-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  grid-template-rows: repeat(10, 1fr);
  gap: 0.3rem;
  width: min(30rem, 100%);
  aspect-ratio: 1;
  margin: 0 auto 0.5rem;
  padding: 0.75rem;
  background: var(--panel-muted);
  border-radius: var(--radius-lg);
}

.apple-cell {
  aspect-ratio: 1;
  border: 1.5px solid var(--edge);
  border-radius: 50%;
  position: relative;
  background: var(--panel);
  transition: border-color 180ms ease, background-color 180ms ease;
}

.apple-svg {
  position: absolute;
  inset: 8%;
  width: 84%;
  height: 84%;
  opacity: 0;
  transition: opacity 220ms ease;
  pointer-events: none;
}

.apple-cell--filled {
  border-color: transparent;
  background: transparent;
}

.apple-cell--filled .apple-svg {
  opacity: 1;
}

/* Number pads */

.pads-row {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
  margin-top: 0.5rem;
}

.pad-col {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  min-width: 13rem;
}

.pad-col--wide {
  min-width: 16rem;
  max-width: 28rem;
  margin: 0 auto;
}

.pad-label {
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-soft);
  margin: 0;
}

.num-pad {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.45rem;
  width: 100%;
}

.num-pad.locked {
  pointer-events: none;
}

.pad-btn {
  font: inherit;
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 800;
  padding: 0.7rem 0.25rem;
  min-height: 2.75rem;
  border: 2px solid var(--edge);
  border-radius: var(--radius-md);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  transition:
    background-color 160ms ease,
    border-color 160ms ease,
    color 160ms ease,
    transform 80ms ease;
  font-variant-numeric: tabular-nums;
}

.pad-btn:hover {
  background: var(--panel-muted);
  border-color: var(--edge-strong);
}

.pad-btn:active {
  transform: scale(0.96);
}

.pad-btn.active {
  background: var(--coral-soft);
  border-color: var(--coral);
  color: var(--coral-dark);
}

.pad-btn.correct {
  background: var(--success);
  border-color: var(--success-dark);
  color: #ffffff;
  animation: flashCorrect 600ms ease;
}

.pad-btn.wrong {
  background: var(--danger);
  border-color: var(--danger-dark);
  color: #ffffff;
  animation: flashWrong 600ms ease;
}

.pad-btn:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: 2px;
}

@keyframes flashCorrect {
  0% {
    transform: scale(1);
  }
  40% {
    transform: scale(1.12);
  }
  100% {
    transform: scale(1);
  }
}

@keyframes flashWrong {
  0%,
  100% {
    transform: translateX(0);
  }
  20% {
    transform: translateX(-6px);
  }
  40% {
    transform: translateX(6px);
  }
  60% {
    transform: translateX(-4px);
  }
  80% {
    transform: translateX(4px);
  }
}

/* Part-whole diagram */

.partwhole-diagram {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 0.6rem;
  min-height: 7rem;
  padding: 1rem;
  background: var(--panel-muted);
  border-radius: var(--radius-lg);
  margin: 0 auto 0.5rem;
  max-width: 44rem;
}

.pw-header {
  width: 100%;
  text-align: center;
  font-family: var(--font-display);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--ink-soft);
  margin: 0 0 0.75rem;
}

.pw-box {
  width: 4.5rem;
  height: 4.5rem;
  border: 3px solid var(--coral);
  border-radius: var(--radius-md);
  background: var(--coral-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.5rem;
  color: var(--coral-dark);
  font-variant-numeric: tabular-nums;
  box-shadow: var(--shadow-sm);
}

.pw-box--empty {
  background: var(--panel);
  color: var(--ink-faint);
}

.pw-box--dividend {
  width: auto;
  min-width: 8rem;
  height: auto;
  padding: 1rem 1.5rem;
  font-size: 2rem;
}

.pw-overflow {
  font-family: var(--font-display);
  font-size: 1rem;
  color: var(--ink-soft);
  font-weight: 700;
  padding: 0 0.5rem;
}

/* Feedback */

.feedback {
  text-align: center;
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 700;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  margin: 1rem auto 0;
  max-width: 32rem;
  transition: background-color 160ms ease, color 160ms ease;
}

.feedback.correct {
  background: var(--success-soft);
  color: var(--success-dark);
}

.feedback.wrong {
  background: var(--danger-soft);
  color: var(--danger-dark);
}

/* Summary */

.summary-text {
  font-family: var(--font-display);
  font-size: 1.25rem;
  text-align: center;
  color: var(--ink);
  max-width: 32rem;
  margin: 1rem auto 2rem;
}

.summary-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* Tab bar — promoted to the spec's footer treatment */

.tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--tab-bar-height);
  background: var(--ink);
  display: flex;
  z-index: 100;
  box-shadow: 0 -4px 16px rgba(46, 43, 43, 0.18);
}

.tab-btn {
  flex: 1;
  border: none;
  background: transparent;
  font: inherit;
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: rgba(255, 255, 255, 0.6);
  cursor: pointer;
  transition: color 120ms ease, background-color 120ms ease;
  padding: 0.5rem;
  position: relative;
}

.tab-btn:hover {
  background: rgba(255, 255, 255, 0.08);
  color: #ffffff;
}

.tab-btn.active {
  color: #ffffff;
}

.tab-btn.active::after {
  content: "";
  position: absolute;
  left: 25%;
  right: 25%;
  bottom: 8px;
  height: 3px;
  background: var(--coral);
  border-radius: 2px;
}

.tab-btn:focus-visible {
  outline: 3px solid var(--coral);
  outline-offset: -3px;
}

/* -- Responsive -- */

@media (max-width: 640px) {
  body {
    padding: 0;
  }

  .app {
    padding: 0.5rem 0.5rem calc(var(--tab-bar-height) + 1rem);
  }

  .screen {
    padding: 1.25rem 0.875rem;
    min-height: auto;
  }

  .game-header-row {
    font-size: 0.75rem;
  }

  .pads-row {
    gap: 0.75rem;
  }

  .pad-col {
    min-width: 100%;
  }

  .num-pad {
    grid-template-columns: repeat(5, 1fr);
    gap: 0.35rem;
  }

  .pw-box {
    width: 3.25rem;
    height: 3.25rem;
    font-size: 1.2rem;
  }

  .tab-btn {
    font-size: 0.7rem;
    letter-spacing: 0.06em;
  }

  .player-row {
    flex-direction: column;
    align-items: flex-start;
  }

  .progress-table {
    font-size: 0.9rem;
  }

  .progress-table th,
  .progress-table td {
    padding: 0.5rem;
  }
}

/* -- Motion preferences -- */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    transition: none !important;
    animation: none !important;
  }
}