header {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 1;
}

header a {
  display: block;
  width: 40px;
  height: 40px;
  background-color: #ffc600;
  border-radius: 50%;
  padding: 10px;
  transition: all 0.5s ease-in-out;
}

header a:hover {
  transform: scale(1.1);
}

header img {
  width: 100%;
}