CSS2是CSS（层叠样式表）的第二级，W3C组织于1998年推出的技术规范，提供了比CSS1更强的XML和HTML文档的格式化功能。例如，元素的扩展定位与可视格式化、页面格式与列印支持和声音样式单等。
基本介绍
- 中文名层叠样式表2级
- 外文名Cascading Style Sheets Level 2
- 推出时间1998年5月
产生背景
样式单自从CSS1的版本之后，又在1998年5月发布了CSS2版本，样式单得到了更多的充实。
CSS2是一套全新的样式表结构，是由W3C推行的，同以往的CSS1完全不一样，CSS2推荐的是一套内容和表现效果分离的方式，HTML元素可以通过CSS2的样式控制显示效果，可完全不使用以往HTML中的table和td来定位表单的外观和样式，只需使用div和li此类HTML标籤来分割元素，之后即可通过CSS2样式来定义表单界面的外观。
使用单位
颜色单位
rgb(R,G,B) #RRGGBB Color Name
时间单位
s ms
频率单位
kHz Hz
标準属性
| 属性 | 取值 | 初值 | 适用于 （默认所有） | 继承性 | 百分比 （默认N/A） | 媒体 |
|---|---|---|---|---|---|---|
azimuth | <angle> | [[ left-side | far-left | left | center-left | center | center-right | right | far-right | right-side ] || behind ] | leftwards | rightwards | inherit | center | yes | aural | ||
background | [background-color || background-image || background-repeat || background-attachment || background-position] | inherit | XX | no | allowed on 'background-position' | visual | |
background-attachment | scroll | fixed | inherit | scroll | no | visual | ||
background-color | <color> | transparent | inherit | transparent | no | visual | ||
background-image | <uri> | none | inherit | none | no | visual | ||
background-position | [ [<percentage> | <length> ]{1,2} | [ [top | center | bottom] || [left | center | right] ] ] | inherit | 0% 0% | block-level and replaced elements | no | refer to the size of the box itself | visual |
background-repeat | repeat | repeat-x | repeat-y | no-repeat | inherit | repeat | no | visual | ||
border | [ border-width || border-style || <color> ] | inherit | see individual properties | no | visual | ||
border-collapse | collapse | separate | inherit | collapse | 'table' and 'inline-table' elements | yes | visual | |
border-color | <color>{1,4} | transparent | inherit | see individual properties | no | visual | ||
border-spacing | <length> <length>? | inherit | 0 | 'table' and 'inline-table' elements | yes | visual | |
border-style | <border-style>{1,4} | inherit | see individual properties | no | visual | ||
border-top border-right border-bottom border-left | [ border-top-width || border-style || <color> ] | inherit | see individual properties | no | visual | ||
border-top-color border-right-color border-bottom-color border-left-color | <color> | inherit | the value of the 'color' property | no | visual | ||
border-top-style border-right-style border-bottom-style border-left-style | <border-style> | inherit | none | no | visual | ||
border-top-width border-right-width border-bottom-width border-left-width | <border-width> | inherit | medium | no | visual | ||
border-width | <border-width>{1,4} | inherit | see individual properties | no | visual | ||
bottom | <length> | <percentage> | auto | inherit | auto | positioned elements | no | refer to height of containing block | visual |
caption-side | top | bottom | left | right | inherit | top | 'table-caption' elements | yes | visual | |
clear | none | left | right | both | inherit | none | block-level elements | no | visual | |
clip | <shape> | auto | inherit | auto | block-level and replaced elements | no | visual | |
color | <color> | inherit | depends on user agent | yes | visual | ||
content | [ <string> | <uri> | <counter> | attr(X) | open-quote | close-quote | no-open-quote | no-close-quote ]+ | inherit | empty string | :before and :after pseudo-elements | no | all | |
counter-increment | [ <identifier> <integer>? ]+ | none | inherit | none | no | all | ||
counter-reset | [ <identifier> <integer>? ]+ | none | inherit | none | no | all | ||
cue | [ cue-before || cue-after ] | inherit | XX | no | aural | ||
cue-after | <uri> | none | inherit | none | no | aural | ||
cue-before | <uri> | none | inherit | none | no | aural | ||
cursor | [ [<uri> ,] [ auto | crosshair | default | pointer | move | e-resize | ne-resize | nw-resize | n-resize | se-resize | sw-resize | s-resize | w-resize| text | wait | help ] ] | inherit | auto | yes | visual, interactive | ||
direction | ltr | rtl | inherit | ltr | all elements, but see prose | yes | visual | |
display | inline | block | list-item | run-in | compact | marker | table | inline-table | table-row-group | table-header-group | table-footer-group | table-row | table-column-group | table-column | table-cell | table-caption | none | inherit | inline | no | all | ||
elevation | <angle> | below | level | above | higher | lower | inherit | level | yes | aural | ||
empty-cells | show | hide | inherit | show | 'table-cell' elements | yes | visual | |
float | left | right | none | inherit | none | all but positioned elements and generated content | no | visual | |
font | [ [ font-style || font-variant || font-weight ]? font-size [ / line-height ]? font-family ] | caption | icon | menu | message-box | small-caption | status-bar | inherit | see individual properties | yes | allowed on 'font-size' and 'line-height' | visual | |
font-family | [[ <family-name> | <generic-family> ],] [<family-name> | <generic-family>] | inherit | depends on user agent | yes | visual | ||
font-size | <absolute-size> | <relative-size> | <length> | <percentage> | inherit | medium | yes, the computed value is inherited | refer to parent element's font size | visual | |
font-size-adjust | <number> | none | inherit | none | yes | visual | ||
font-stretch | normal | wider | narrower | ultra-condensed | extra-condensed | condensed | semi-condensed | semi-expanded | expanded | extra-expanded | ultra-expanded | inherit | normal | yes | visual | ||
font-style | normal | italic | oblique | inherit | normal | yes | visual | ||
font-variant | normal | small-caps | inherit | normal | yes | visual | ||
font-weight | normal | bold | bolder | lighter | 100 |、 200 | 300、 | 400 |、 500、 | 600 | 700 、| 800 | 900 | inherit | normal | yes | visual | ||
height | <length> | <percentage> | auto | inherit | auto | all elements but non-replaced inline elements, table columns, and column groups | no | see prose | visual |
left | <length> | <percentage> | auto | inherit | auto | positioned elements | no | refer to width of containing block | visual |
letter-spacing | normal | <length> | inherit | normal | yes | visual | ||
line-height | normal | <number> | <length> | <percentage> | inherit | normal | yes | refer to the font size of the element itself | visual | |
list-style | [ list-style-type || list-style-position || list-style-image ] | inherit | XX | elements with 'display: list-item' | yes | visual | |
list-style-image | <uri> | none | inherit | none | elements with 'display: list-item' | yes | visual | |
list-style-position | inside | outside | inherit | outside | elements with 'display: list-item' | yes | visual | |
list-style-type | disc | circle | square | decimal | decimal-leading-zero | lower-roman | upper-roman | lower-greek | lower-alpha | lower-latin | upper-alpha | upper-latin | hebrew | armenian | georgian | cjk-ideographic | hiragana | katakana | hiragana-iroha | katakana-iroha | none | inherit | disc | elements with 'display: list-item' | yes | visual | |
margin | <margin-width>{1,4} | inherit | XX | no | refer to width of containing block | visual | |
margin-top margin-right margin-bottom margin-left | <margin-width> | inherit | 0 | no | refer to width of containing block | visual | |
marker-offset | <length> | auto | inherit | auto | elements with 'display: marker' | no | visual | |
marks | [ crop || cross ] | none | inherit | none | page context | N/A | visual, paged | |
max-height | <length> | <percentage> | none | inherit | none | all elements except non-replaced inline elements and table elements | no | refer to height of containing block | visual |
max-width | <length> | <percentage> | none | inherit | none | all elements except non-replaced inline elements and table elements | no | refer to width of containing block | visual |
min-height | <length> | <percentage> | inherit | 0 | all elements except non-replaced inline elements and table elements | no | refer to height of containing block | visual |
min-width | <length> | <percentage> | inherit | UA dependent | all elements except non-replaced inline elements and table elements | no | refer to width of containing block | visual |
orphans | <integer> | inherit | 2 | block-level elements | yes | visual, paged | |
outline | [ outline-color || outline-style || outline-width ] | inherit | see individual properties | no | visual, interactive | ||
outline-color | <color> | invert | inherit | invert | no | visual, interactive | ||
outline-style | <border-style> | inherit | none | no | visual, interactive | ||
outline-width | <border-width> | inherit | medium | no | visual, interactive | ||
overflow | visible | hidden | scroll | auto | inherit | visible | block-level and replaced elements | no | visual | |
padding | <padding-width>{1,4} | inherit | XX | no | refer to width of containing block | visual | |
padding-top padding-right padding-bottom padding-left | <padding-width> | inherit | 0 | no | refer to width of containing block | visual | |
page | <identifier> | auto | auto | block-level elements | yes | visual, paged | |
page-break-after | auto | always | avoid | left | right | inherit | auto | block-level elements | no | visual, paged | |
page-break-before | auto | always | avoid | left | right | inherit | auto | block-level elements | no | visual, paged | |
page-break-inside | avoid | auto | inherit | auto | block-level elements | yes | visual, paged | |
pause | [ [<time> | <percentage>]{1,2} ] | inherit | depends on user agent | no | see descriptions of 'pause-before' and 'pause-after' | aural | |
pause-after | <time> | <percentage> | inherit | depends on user agent | no | see prose | aural | |
pause-before | <time> | <percentage> | inherit | depends on user agent | no | see prose | aural | |
pitch | <frequency> | x-low | low | medium | high | x-high | inherit | medium | yes | aural | ||
pitch-range | <number> | inherit | 50 | yes | aural | ||
play-during | <uri> mix? repeat? | auto | none | inherit | auto | no | aural | ||
position | static | relative | absolute | fixed | inherit | static | all elements, but not to generated content | no | visual | |
quotes | [<string> <string>]+ | none | inherit | depends on user agent | yes | visual | ||
richness | <number> | inherit | 50 | yes | aural | ||
right | <length> | <percentage> | auto | inherit | auto | positioned elements | no | refer to width of containing block | visual |
size | <length>{1,2} | auto | portrait | landscape | inherit | auto | the page context | N/A | visual, paged | |
speak | normal | none | spell-out | inherit | normal | yes | aural | ||
speak-header | once | always | inherit | once | elements that have table header information | yes | aural | |
speak-numeral | digits | continuous | inherit | continuous | yes | aural | ||
speak-punctuation | code | none | inherit | none | yes | aural | ||
speech-rate | <number> | x-slow | slow | medium | fast | x-fast | faster | slower | inherit | medium | yes | aural | ||
stress | <number> | inherit | 50 | yes | aural | ||
table-layout | auto | fixed | inherit | auto | 'table' and 'inline-table' elements | no | visual | |
text-align | left | right | center | justify | <string> | inherit | depends on user agent and writing direction | block-level elements | yes | visual | |
text-decoration | none | [ underline || overline || line-through || blink ] | inherit | none | no (see prose) | visual | ||
text-indent | <length> | <percentage> | inherit | 0 | block-level elements | yes | refer to width of containing block | visual |
text-shadow | none | [<color> || <length> <length> <length>? ,] [<color> || <length> <length> <length>?] | inherit | none | no (see prose) | visual | ||
text-transform | capitalize | uppercase | lowercase | none | inherit | none | yes | visual | ||
top | <length> | <percentage> | auto | inherit | auto | positioned elements | no | refer to height of containing block | visual |
unicode-bidi | normal | embed | bidi-override | inherit | normal | all elements, but see prose | no | visual | |
vertical-align | baseline | sub | super | top | text-top | middle | bottom | text-bottom | <percentage> | <length> | inherit | baseline | inline-level and 'table-cell' elements | no | refer to the 'line-height' of the element itself | visual |
visibility | visible | hidden | collapse | inherit | inherit | no | visual | ||
voice-family | [[<specific-voice> | <generic-voice> ],] [<specific-voice> | <generic-voice> ] | inherit | depends on user agent | yes | aural | ||
volume | <number> | <percentage> | silent | x-soft | soft | medium | loud | x-loud | inherit | medium | yes | refer to inherited value | aural | |
white-space | normal | pre | nowrap | inherit | normal | block-level elements | yes | visual | |
widows | <integer> | inherit | 2 | block-level elements | yes | visual, paged | |
width | <length> | <percentage> | auto | inherit | auto | all elements but non-replaced inline elements, table rows, and row groups | no | refer to width of containing block | visual |
word-spacing | normal | <length> | inherit | normal | yes | visual | ||
z-index | auto | <integer> | inherit | auto | positioned elements | no | visual |
性能评价
CSS2规范在很大程度上扩展了CSS1中所完成的工作。它包括数十种新的属性（和伪元素），以及现有属性的很多附加值。
CSS2合併和精炼了用来定位的属性系列，让设计者可以更多地控制页面布局，DHTML作者可以创建动态动作效果。它比传统的排版元素，诸如短行、孤立行以及分页，提供了更多的控制。这表示样式表的发展已经考虑到了文档的HTML显示和列印两个方面。
CSS2还引入了一些属性，可以对表格元素外观提供附加的控制。作为W3C对提高网页可访性所做工作的一部分，新的样式表规范包括了很多专门针对非可视化网页显示的属性。这些新的属性提供了对语音传送和声音的控制。
遗憾的是其中的大多数样式规则在当时的浏览器中没有得到广泛的支持，在后来的CSS2.1中一部分被修改了，还有一部分被删掉了（像text-shadow属性在CSS2中被引入，CSS2.1中被删除，却在CSS3中又被引入）。