body {
  font-family: Arial, Helvetica, sans-serif;
  background-color: #f4f6f8;
  margin: 0;
  padding: 0;
}
.container {
  width: 65%;
  margin: 60px auto;
  background: white;
  padding: 30px;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
h1 {
  text-align: center;
  color: #333;
}
.subtitle {
  text-align: center;
  color: #666;
  margin-bottom: 30px;
}
.topics {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
  justify-content: center;
}

.topics button {
  padding: 12px 20px;
  border: none;
  border-radius: 6px;
  background-color: #4a6cf7;
  color: white;
  font-size: 15px;
  cursor: pointer;
}
.topics button:hover {
  background-color: #3b5bdb;
}

#output {
  margin-top: 30px;
  padding: 20px;
  background-color: #eef2f5;
  border-radius: 6px;
  font-size: 16px;
  line-height: 1.6;
}