header {
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  padding: 20px 0;
}

.PB {
  font-size: 24px;
}

nav {
  position: absolute;
  top: 20px;
  right: 40px;
}

nav a {
  text-decoration: none;
  color: #004aad;
  font-weight: bold;
  margin-left: 20px;
  font-size: 18px;
  transition: color 0.3s, border-bottom 0.3s;
}

nav a:hover {
  border-bottom: 2px solid #000000;
}

main {
  background-color: rgba(0, 0, 0, 0.5);
  padding: 30px;
  max-width: 800px;
  margin: 40px auto;
  border-radius: 10px;
  outline: 2px solid rgb(0, 0, 0);
}

article {
  background-color: #fffdfd;
}

footer {
  position: fixed;
  bottom: 0;
  width: 100%;
  text-align: center;
  background-color: #f0f0f0;
  padding: 1rem;
}