* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background-color: #0f172a;
  color: #e2e8f0;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: stretch;
  padding: 1.5rem;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

.app {
  display: grid;
  gap: 2rem;
  grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
  width: min(1100px, 100%);
}

.app__game,
.app__info {
  background-color: #1e293b;
  border-radius: 1rem;
  padding: 1.5rem;
  box-shadow: 0 20px 60px rgba(15, 23, 42, 0.35);
}

.app__title {
  margin: 0;
  font-size: 2rem;
  font-weight: 700;
}

.app__subtitle {
  margin: 0.25rem 0 0;
  color: #94a3b8;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 1.5rem 0;
}

.control-button {
  background: linear-gradient(135deg, #22d3ee, #2563eb);
  border: none;
  border-radius: 999px;
  color: #0f172a;
  cursor: pointer;
  font-size: 1rem;
  font-weight: 600;
  padding: 0.75rem 1.5rem;
  transition: transform 120ms ease, box-shadow 120ms ease;
}

.control-button:hover,
.control-button:focus {
  transform: translateY(-1px);
  box-shadow: 0 10px 25px rgba(37, 99, 235, 0.45);
}

.control-button:active {
  transform: translateY(0);
  box-shadow: none;
}

.control-button--secondary {
  background: #334155;
  color: #e2e8f0;
}

.status {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.status__message {
  min-height: 1.5rem;
  margin: 0;
  color: #f8fafc;
  font-weight: 600;
}

.status__message.status__message--error {
  color: #f87171;
}

.status__message.status__message--success {
  color: #4ade80;
}

.status__metrics {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  color: #cbd5f5;
}

.status__metric {
  font-size: 0.95rem;
}

.board {
  margin-top: 1.5rem;
  display: grid;
  gap: 0.5rem;
  width: 100%;
}

.board-actions {
  margin-top: 1.25rem;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.75rem;
}

.board-action {
  width: 3.5rem;
  height: 3.5rem;
  border-radius: 50%;
  border: none;
  display: inline-flex;
  justify-content: center;
  align-items: center;
  font-size: 2rem;
  font-weight: 700;
  cursor: pointer;
  color: #0f172a;
  transition: transform 120ms ease, box-shadow 120ms ease, background 120ms ease;
  position: relative;
}

.board-action:hover,
.board-action:focus {
  transform: translateY(-2px);
  box-shadow: 0 16px 30px rgba(15, 23, 42, 0.35);
}

.board-action:active {
  transform: translateY(0);
  box-shadow: none;
}

.board-action--primary {
  background: linear-gradient(135deg, #22d3ee, #2563eb);
}

.board-action--secondary {
  background: #e2e8f0;
  color: #0f172a;
}

.board-action__icon {
  line-height: 1;
}

.board-action__badge {
  position: absolute;
  top: -0.35rem;
  right: -0.35rem;
  min-width: 1.5rem;
  padding: 0.15rem 0.4rem;
  border-radius: 999px;
  background: #0ea5e9;
  color: #0f172a;
  font-size: 0.85rem;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 14px rgba(14, 165, 233, 0.45);
}

.board-action__badge.board-action__badge--empty {
  background: #cbd5f5;
  color: #475569;
  box-shadow: none;
}

.board-action--attention {
  box-shadow: 0 0 0 4px rgba(34, 211, 238, 0.4), 0 18px 36px rgba(8, 145, 178, 0.45);
  animation: board-action-pulse 0.9s ease-in-out infinite alternate;
}

@keyframes board-action-pulse {
  from {
    transform: translateY(-2px) scale(1);
  }
  to {
    transform: translateY(-3px) scale(1.05);
  }
}

.tile {
  width: 100%;
  aspect-ratio: 1 / 1;
  border-radius: 0.75rem;
  border: none;
  font-size: clamp(1.125rem, 4vw, 1.5rem);
  font-weight: 700;
  color: #0f172a;
  background: linear-gradient(145deg, #f1f5f9, #cbd5f5);
  cursor: pointer;
  transition: transform 120ms ease, box-shadow 120ms ease, background 120ms ease;
  display: flex;
  justify-content: center;
  align-items: center;
}

.tile:hover,
.tile:focus {
  transform: translateY(-2px);
  box-shadow: 0 14px 25px rgba(15, 23, 42, 0.35);
}

.tile--selected {
  background: linear-gradient(145deg, #fde68a, #f97316);
  box-shadow: 0 16px 35px rgba(251, 191, 36, 0.4);
}

.tile--hinted:not(.tile--selected) {
  background: linear-gradient(145deg, #bfdbfe, #93c5fd);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.5), 0 12px 24px rgba(37, 99, 235, 0.35);
}

.tile--empty {
  background: rgba(148, 163, 184, 0.25);
  border: 1px dashed rgba(148, 163, 184, 0.45);
  cursor: default;
  box-shadow: none;
}

.tile--empty:hover,
.tile--empty:focus {
  transform: none;
}

.app__info h2,
.app__info h3 {
  margin-top: 0;
  color: #f8fafc;
}

.app__info ul {
  padding-left: 1.25rem;
  margin: 0.75rem 0 1rem;
}

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

.app__info p {
  color: #cbd5f5;
  line-height: 1.5;
}

@media (max-width: 960px) {
  body {
    padding: 0;
  }

  .app {
    grid-template-columns: minmax(0, 1fr);
    gap: 1.25rem;
  }

  .app__info {
    order: 1;
    margin-top: 0;
  }

  .board {
    gap: 0.35rem;
  }

  .board-actions {
    margin-top: 1rem;
    gap: 0.5rem;
  }

  .board-action {
    width: 3.1rem;
    height: 3.1rem;
    font-size: 1.75rem;
  }

  .board-action__badge {
    top: -0.25rem;
    right: -0.25rem;
    min-width: 1.35rem;
    font-size: 0.75rem;
  }
}