The background background shorthand form is
Backgroud:background-color background-position background-size background-repeat background-origin background-clip Background-attachment Background-image
which
Background-color background Color
Background-position the position of the image is two values, string words, the first represents a vertical direction, the value includes Top.bottom.center. The second represents a horizontal direction, and the value includes Left.right.center. The number of units or percentages, the first represents the horizontal direction, such as 10px distance from the left edge of 10px, the second represents a vertical direction, such as 10%, the height distance from the upper boundary 10%, the top is 0. The bottom is 100%.
Background-size background size, four desirable values.
Number Unit Number unit The first is the width, the second is the height, if only one is set, and the other is auto. 20px 20px
Percent percent as above
Contain scale images,
CSS setting element background (to be continued)