body {
  font-family: Arial, sans-serif;
  text-align: center;
  margin: 0;
  padding: 0;
  background: white;
  color: black;
  transition: background 2s, color 2s;
}
canvas {
  background: white;
  display: block;
  margin: 20px auto;
  border: 2px solid #000;
}
#startBtn {
  padding: 10px 20px;
  font-size: 18px;
  border: none;
  background: crimson;
  color: white;
  border-radius: 8px;
  cursor: pointer;
  display: none;
}
#message {
  margin-top: 20px;
  font-size: 24px;
  font-weight: bold;
}
#celebration {
  font-size: 36px;
  font-weight: bold;
  opacity: 0;
  transform: translateY(50px);
  transition: all 2s;
}
#tribute {
  margin: 20px auto;
  max-width: 700px;
  font-size: 20px;
  line-height: 1.6;
  opacity: 0;
  white-space: pre-wrap;
  text-align: justify;
}
/* Responsive cho mobile */
@media (max-width: 768px) {
  #message {
    font-size: 18px;
    padding: 0 10px;
  }
  #startBtn {
    font-size: 16px;
    padding: 8px 16px;
  }
  #celebration {
    font-size: 24px;
  }
  #tribute {
    font-size: 16px;
    line-height: 1.5;
    padding: 0 12px;
    text-align: left;
  }
  canvas {
    width: 95%;
    height: auto;
  }
}