body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: black;
  color: #333;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
  text-align: center;
}

header {
  background-color: black;
  color: white;
  padding: 20px 0;
}

header h1 {
  color: lime;
  margin: 0;
  font-size: 2em;
}

header p {
   color: red;
  margin: 0;
  font-size: 1.2em;
}

main {
  margin-top: 20px;
}

.guide, .music-player, .breathing-exercise, .optical-simulation {
  background-color: white;
  border-radius: 8px;
  padding: 20px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  margin-bottom: 20px;
}

h2 {
  font-size: 1.5em;
  margin-bottom: 10px;
}

button {
  background-color: #4caf50;
  color: white;
  border: none;
  padding: 10px 15px;
  border-radius: 5px;
  cursor: pointer;
  font-size: 1em;
}

button:hover {
  background-color: #45a049;
}

#optical-animation {
  width: 100%;
  height: 200px;
  margin-top: 20px;
  background: linear-gradient(90deg, #ff0000, #ff7e00, #fffb00, #00ff00, #0000ff, #ff00ff);
  animation: passion-pulse 5s infinite ease-in-out;
  border-radius: 50px; /* স্ফীত আকৃতি */
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.3); /* গভীর ছায়া */
}

@keyframes passion-pulse {
  0% {
    transform: scale(1); /* প্রাথমিক আকার */
    background: linear-gradient(90deg, #ff0000, #ff7e00, #fffb00, #00ff00, #0000ff, #ff00ff);
  }
  25% {
    transform: scale(1.05); /* ধীরে ধীরে বেড়ে যাওয়া */
    background: linear-gradient(90deg, #ff7e00, #fffb00, #00ff00, #0000ff, #ff00ff, #ff0000);
  }
  50% {
    transform: scale(1.1); /* আরও বৃদ্ধি */
    background: linear-gradient(90deg, #fffb00, #00ff00, #0000ff, #ff00ff, #ff0000, #ff7e00);
  }
  75% {
    transform: scale(1.05); /* আবার ছোট হওয়া */
    background: linear-gradient(90deg, #00ff00, #0000ff, #ff00ff, #ff0000, #ff7e00, #fffb00);
  }
  100% {
    transform: scale(1); /* প্রাথমিক আকারে ফিরে আসা */
    background: linear-gradient(90deg, #ff0000, #ff7e00, #fffb00, #00ff00, #0000ff, #ff00ff);
  }
}