body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f8f9fa;
  color: #333;
}

header {
  text-align: center;
  padding: 50px 0;
  background-color: #007bff;
  color: #fff;
}

header h1 {
  font-size: 36px;
  margin-bottom: 10px;
}

header img {
  width: 250px;
  border-radius: 50%;
}

nav#links {
  text-align: center;
  margin-top: 50px;
}

nav#links h2 {
  font-size: 24px;
}

nav#links ul {
  list-style-type: none;
  padding: 0;
}

nav#links ul li {
  display: inline-block;
  margin: 0 10px;
}

nav#links button {
  background-color: transparent;
  border: none;
  cursor: pointer;
  transition: transform 0.3s ease;
}

nav#links button img {
  width: 50px;
}

nav#links button:hover {
  transform: translateY(-3px);
}

main {
  text-align: center;
  margin-top: 50px;
}

main h2 {
  font-size: 24px;
}

.papers-container {
  list-style-type: none;
  padding: 0;
  margin: 0 auto;
  max-width: 600px;
  /* 幅を指定 */
}

.papers-container li {
  margin-bottom: 20px;
}

.papers-container a {
  display: block;
  padding: 15px;
  background-color: #fff;
  color: #666666;
  text-decoration: none;
  border-radius: 10px;
  /* box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1); */
  transition: transform 0.3s ease;
}

.papers-container a:hover {
  transform: translateY(-3px);
}