header {
  position: fixed;
  z-index: 99;
  top: 0;
}
main {
  margin-top: 20vh;
}
#input {
  position: fixed;
  z-index: 99;
  top: 10vh;
  display: flex;
  justify-content: center;
  left: 50%;
  transform: translateX(-50%);
  background-color: white;
}
ul button {
  max-width: 120px;
}

@media (max-width: 400) {
  .hide {
    display: none;
  }
}