See the Pen background-clip by nilgi (@nilgi) on CodePen.
• background-clip: border-box; / 기본값. 테두리 가장자리까지
• background-clip: padding-box; / 안쪽여백 가장자리까지
• background-clip: content-box; / 컨텐츠만 칠하기
• background-clip: text; / 글자만
-webkit-background-clip: text;
color: transparent;