html&css : Layout

position: 

position: absolute;

스크롤링하면 따라서 올라감. 

position: fixed;

스크롤링해도 설정한 이미지는 화면 내 설정한 위치에 고정된다.

z-index:

float: 

float: left;

float: right;

clear:

1. left — the left side of the element will not touch any other element within the same containing element.
2. right — the right side of the element will not touch any other element within the same containing element.
3. both — neither side of the element will touch any other element within the same containing element.
4. none — the element can touch either side.