contenteditable=\'true\'를 사용하여 div에 자리 표시자 텍스트를 추가합니다.

div[contenteditable] {
  &[placeholder]:empty::before {
    content: attr(placeholder);
    z-index: 9;
    line-height: 1.7;
    color: #555;
    word-break: break-all;
    user-select: none;
  }

  &[placeholder]:empty:focus::before {
    content: "";
  }
}

<div contenteditable="true" placeholder="Subscribe to Axorax on YT! :D"></div>

div[contenteditable] {
  /* Basic styles */
  width: 20rem;
  height: 15rem;
  padding: 1rem;
  background: #292929;
  color: #fff;

  /* Placeholder code */
  &[placeholder]:empty::before {
    content: attr(placeholder);
    z-index: 9;
    line-height: 1.7;
    color: #555;
    word-break: break-all;
    user-select: none;
  }

  &[placeholder]:empty:focus::before {
    content: "";
  }
}