body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  max-width: 650px;
  margin: 60px auto;
  line-height: 1.6;
  padding: 0 20px;
  color: #222;
}

nav {
  margin-bottom: 40px;
  font-size: 0.9em;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.game-shell {
  border: 1px solid #e6e6e6;
  border-radius: 12px;
  padding: 20px;
  margin-top: 20px;
  background: #fafafa;
}

.small-note {
  font-size: 0.95rem;
  color: #444;
}

.hud {
  display: flex;
  gap: 18px;
  flex-wrap: wrap;
  margin: 18px 0;
}

.hud > div {
  background: #fff;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 8px 12px;
  min-width: 90px;
}

.label {
  display: block;
  font-size: 0.75rem;
  color: #666;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.problem-row {
  margin: 16px 0;
}

.problem {
  font-size: 1.35rem;
  margin-bottom: 8px;
}

input[type="number"] {
  width: 160px;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 8px;
  font-size: 1rem;
}

.button-row {
  margin-top: 10px;
  display: flex;
  gap: 8px;
}

button {
  border: 1px solid #111;
  background: #111;
  color: #fff;
  border-radius: 8px;
  padding: 8px 12px;
  cursor: pointer;
}

button[disabled] {
  opacity: 0.55;
  cursor: not-allowed;
}

.status-msg {
  min-height: 24px;
  font-weight: 600;
}

.leaderboard-wrap {
  margin-top: 20px;
}

.leaderboard-list {
  padding-left: 20px;
}

.brag-banner {
  display: none;
  margin-top: 16px;
  border-radius: 8px;
  padding: 12px;
  text-align: center;
  font-weight: 800;
  letter-spacing: 1px;
  background: linear-gradient(90deg, #ffe55c, #ff8a5b);
}

.brag-banner.show {
  display: block;
  animation: bragPulse 0.5s ease-in-out 4 alternate;
}

body.page-explode {
  animation: shake 0.35s linear 6;
  background: radial-gradient(circle at center, #fff4e1 0%, #ffffff 70%);
}

@keyframes shake {
  0% { transform: translate(0, 0) rotate(0deg); }
  25% { transform: translate(2px, -2px) rotate(-0.6deg); }
  50% { transform: translate(-3px, 2px) rotate(0.4deg); }
  75% { transform: translate(3px, 1px) rotate(-0.4deg); }
  100% { transform: translate(0, 0) rotate(0deg); }
}

@keyframes bragPulse {
  from { transform: scale(1); filter: saturate(1); }
  to { transform: scale(1.03); filter: saturate(1.8); }
}