focus時にplaceholder(プレースホルダー)の値を非表示にする

CSS

input:focus:placeholder-shown {
  color: transparent;
}
input:focus::-webkit-input-placeholder {
  color: transparent;
}
input:focus::-moz-placeholder {
  color: transparent;
}
input:focus:-ms-input-placeholder {
  color: transparent;
}
input:focus::-ms-input-placeholder {
  color: transparent;
}