What are the concepts and grammatical rules of css
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Css
Full name Cascading Style Sheet
Introducing css into html pages
1, written in the head tag
two,
3, embedded styl
Syntax:
Selector {
Attribute name: attribute valu
Proterty1:value
Width:100px
/ * Notes * /
...
Browser private properties
Chrome,safari
-webkit-
Firefox
-moz-
IE
-ms-
Opera
-o-
Attribute value syntax
Padding: [| | auto] {1pm 4}
Grammatical description
1, basic element: refers to key words such as length auto in grammar
2. The combination conforms to: it means that the grammatical descriptions are consistent, and different symbols represent different meanings.
3, quantity symbol: {} and number
Basic elements:
Type: basic type (,.)
Other types (,.)
Symbol: (/,)
Inherit, initial
Combination coincidence
Spaces: the order of numbers must be the same and the number must be the same, as follows
Legal value: 12px arial
Illegal: arial 12px
12px
& &: & & two values must appear and do not need to be in the same order
Legal: green 2px
1em blue
Illegal: 1em
| |: at least one occurs. The order is not required. |
| |: only one of them can appear, not at the same time |
: bold [|] grouping function
Quantity symbol:
None: indicates that the basic element can only appear once
+: appear one or more times [,] +
Legal values: # fff, red, gray
? : may or may not appear as an optional inset? & &
Inset blue
Red
{}: indicates that the basic element appears at least several times and at most several times {2pr 4}
*: can appear 0J1, or more than once
#: need to appear one or more times, separated by commas multiple times
@ rules
@ identifier xxx
@ identifier xxx {}
Commonly used: @ media
@ keyframes
@ font-face
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