body {
  margin: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: radial-gradient(circle at top, #111 0%, #000 70%);
  font-family: "Segoe UI", sans-serif;
}

.app {
  background: rgba(255, 255, 255, 0.06);
  backdrop-filter: blur(14px);
  border-radius: 16px;
  padding: 40px 45px;
  text-align: center;
  color: #fff;
  box-shadow: 0 0 30px rgba(0, 188, 212, 0.3);
  min-width: 320px;
}

.title {
  margin: 0 0 15px;
  color: #00e5ff;
  letter-spacing: 1px;
}

#display {
  font-size: 60px;
  font-weight: bold;
  margin: 20px 0 30px;
  color: #00ffff;
  text-shadow: 0 0 15px rgba(0, 255, 255, 0.8);
}

.controls {
  display: flex;
  justify-content: center;
  gap: 14px;
}

button {
  padding: 12px 26px;
  border: none;
  border-radius: 999px;
  font-size: 15px;
  cursor: pointer;
  font-weight: 600;
  transition: 0.25s;
}

#startBtn {
  background: #00c853;
  color: #28a745;
}
#stopBtn {
  background: #ff5252;
  color: #dc3545;
}
#resetBtn {
  background: #ffab00;
  color: #ffc107;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 12px rgba(255, 255, 255, 0.4);
}

.credit {
  margin-top: 20px;
  font-size: 13px;
  opacity: 0.7;
}

button {
  font-weight: 600;
  letter-spacing: 0.5px;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
}

.start-btn {
  background: linear-gradient(135deg, #00ff6a, #00cc55);
  box-shadow: 0 0 12px rgba(0, 255, 106, 0.5);
}

.stop-btn {
  background: linear-gradient(135deg, #ff4b4b, #ff1f1f);
  box-shadow: 0 0 12px rgba(255, 75, 75, 0.5);
}

.reset-btn {
  background: linear-gradient(135deg, #ffcc00, #ff9900);
  box-shadow: 0 0 12px rgba(255, 204, 0, 0.5);
  color: #111;
}