body {
  font-family: "Segoe UI", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  background-color: #f6f6f6;
  margin: 0;
  padding: 0;
}

.container {
  max-width: 600px;
  margin: 40px auto;
  background-color: #fff;
  border-radius: 10px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
  padding: 30px;
}

h1 {
  text-align: center;
  font-size: 1.3rem;
  margin-bottom: 20px;
}

.description {
  font-size: 0.95rem;
  margin-bottom: 8px;
  text-align: center;
}

.dropdown {
  width: 100%;
  padding: 8px;
  font-size: 0.95rem;
  margin-bottom: 25px;
  border-radius: 5px;
  border: 1px solid #ccc;
}

.box {
  background-color: #f8f8f8;
  border: 1px solid #ddd;
  border-radius: 8px;
  padding: 15px 20px;
  margin-bottom: 20px;
}

.box h2 {
  font-size: 1rem;
  margin-bottom: 5px;
}

.note {
  font-size: 0.85rem;
  color: #555;
  margin-bottom: 10px;
}

.citation {
  background-color: #fff;
  border: 1px solid #ccc;
  border-radius: 6px;
  padding: 10px;
  font-size: 0.9rem;
  line-height: 1.5;
  margin-bottom: 10px;
}

.copy-btn {
  background-color: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  padding: 8px 16px;
  cursor: pointer;
}

.copy-btn:hover {
  background-color: #005fc3;
}

footer {
  text-align: center;
  font-size: 0.85rem;
  color: #333;
  margin-top: 30px;
}

.close-btn {
  margin-top: 10px;
  background-color: #c70000;
  color: white;
  border: none;
  border-radius: 6px;
  padding: 10px 20px;
  cursor: pointer;
}

.close-btn:hover {
  background-color: #a00000;
}

.copy-btn.success {
  background-color: #28a745 !important; /* 緑色 */
}