:placeholder-shown

/* Selects any <input> or <textarea> element with */
/* a placeholder attribute that is currently displaying */
/* the placeholder */
:placeholder-shown {
  border: 2px solid silver;
}

:placeholder-shown

<input placeholder="Type something here!">

input {
  border: 2px solid black;
  padding: 3px;
}

input:placeholder-shown {
  border-color: silver;
}

<input placeholder="Enter something into this field, if you please!">

input:placeholder-shown {
  text-overflow: ellipsis;
}