footer {
  background-color: #f8f9fa; /* 淡灰色背景 */
  padding: 20px 0;
  font-size: 0.9em;
}

footer a {
  color: #007bff; /* 蓝色链接 */
  text-decoration: none;
}

footer a:hover {
  text-decoration: underline;
}

footer ul {
  list-style: none;
  padding: 0;
}

footer li {
  margin-bottom: 5px;
}

.text-center {
  text-align: center;
}


.jumbotron {
  background-color: #e9ecef; /* 淡灰色背景 */
  padding: 4rem 2rem;
  margin-bottom: 2rem;
  border-radius: 0.3rem;
}

.jumbotron h1 {
  font-weight: bold;
}