web page design simple to add css knowledge

Learn the basic framework of web, html and css, add a few points of knowledge
common representation of colors in several ways:
Red
# f00
rgb (255,0,0)
RGBA (255,0,0,0.5) with transparency color values
opacity: 50%; opacity
border-radius: rounded
border-radius: value
value: a represents the same as the corners are rounded status
values: ab represents the upper left, lower right are a, upper right, lower left, b are
values: abc He expressed as a left upper and lower left upper right lower right b c
value: ABCD represents the upper left upper right lower right bottom left turn
: 50% indicates a circular or elliptical
cursor: pointer; / mouse icon to the hand shape /
positioning all the positioning and top right bottom and function together with left
position: relative;
position: absolute;
right: 0;
left: 0;
relative to a default position relative positioning movement of the reference point,
absolute absolute positioning element positioned nearest to the reference point for the movement of
fixed fixed positioning
positioning in the middle level:
margin: Auto;
box model:
width: width content + border + margin + padding
box-sizing: border-box;
Width: width + margin (width = width content + border + padding)
Image format: JPG GIF PNG WebP
overflow: hidden; hidden overflow
: first-of-type with a first type of object
: nth -of-type (n) of a n n = number type object oDD (odd line) the even (even-numbered rows)
INPUT {
Outline: none;} go outside border