body {
  font-family: Arial, sans-serif;
  background: #f4f6f8;
  margin: 0;

  display: flex;
  justify-content: center;
  align-items: center;

  min-height: 100vh;
}

.container {
  width: 90%;
  max-width: 760px;

  background: white;
  padding: 36px;

  border-radius: 16px;

  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

h2 {
  font-size: 36px;
  margin-top: 0;
  margin-bottom: 28px;
}

.chapter-area {
  margin-bottom: 10px;
  font-size: 22px;
}

select {
  font-size: 20px;
  padding: 4px 8px;
}

#chatbox {
  height: 440px;

  overflow-y: auto;

  border: 1px solid #ddd;

  padding: 16px;

  margin-bottom: 14px;

  background: #ffffff;
}

.message {
  margin: 12px 0;
  font-size: 22px;
  line-height: 1.35;
}

.user {
  text-align: right;
  color: blue;
}

.bot {
  text-align: left;
  color: green;
}

.input-area {
  display: flex;
  gap: 4px;
}

input {
  flex: 1;

  padding: 12px;

  font-size: 18px;

  border: 1px solid #999;
  border-radius: 4px;
}

button {
  padding: 12px 16px;

  font-size: 18px;

  border: 1px solid #999;
  border-radius: 6px;

  cursor: pointer;
}

button:hover {
  background: #e5e7eb;
}

ol {
  margin-top: 10px;
}

li {
  margin-bottom: 8px;
}