header {
  background: linear-gradient(to right, #00FF00, #F4DF4EFF);
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 0;
}

header h1 {
  color:black;
  margin: 0;
  font-style: normal;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
}

nav a {
  position: relative;
  color: black;
  text-decoration: none;
  margin-right: 1rem;
  font-size:20px;
}

nav a:hover {
  color: grey;
}

footer {
  background-color: #949398FF;
  color: black;
  text-align: center;
}

nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -3px;
  width: 0;
  height: 2px;
  background-color: white;
  transition: width 0.3s ease;
}

nav a:hover::after {
  width: 100%;
}