body {
  font-family: Arial, sans-serif;
  margin-top: 90px; /* Adjust this value to match the height of your header */
  margin-bottom: 0; /* Adjust this value to match the height of your footer */
  margin-left: 0;
  margin-right: 0;
  padding: 0;
  background-color: #f4f4f4;
  color: #333;
}

header {
  background-color: #4caf50;
  color: white;
  padding: 10px 0;
  text-align: center;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1000;
}

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

nav ul li {
  display: inline;
  margin: 0 15px;
}

nav ul li a {
  color: white;
  text-decoration: none;
  font-weight: bold;
}

section {
  margin: 20px;
}

footer {
  background-color: #333;
  color: white;
  text-align: center;
  padding: 10px 0;
  position: fixed;
  width: 100%;
  bottom: 0;
}

.abstract p {
  font-size: larger;
  font-weight: 600;
}