background-position 노트
background. background. background.
background-position is used to place the origin image with respect to the padding edge of the element. In other words, the image-placement context is the innner border edge, even though the background area extends to the outer border edge.
그리고,
background-position: 30px; = background-position:30px 50%;
background-position: 25% 35%; = 배경 이미지의 25%오른쪽 35% 아래인 기준점이 엘리먼트의 25%오른쪽 35%아래의 위치로 이동.
ps. in prior to 2.1 css u cannot mix up keywords 예) background-position: top 75% (x)