# opacity
**版本:CSS3**
### 語法:
*<length>* | inherit
### 取值:
*<length>* :由浮點數字和單位標識符組成的長度值。不可為負值。默認值為:1 inherit:默認繼承。
### 說明:
由浮點數字和單位標識符組成的長度值。不可為負值。聲明用來設置一個元素的透明度,opacity取值為1的元素是完全不透明的,反之,取值為0是完全透明的,看不見的。1到0之間的任何值都表示該元素的透明程度。
### 兼容性:
<table><thead><tr><th class="type">類型</th> <th class="type_ie"><img src="https://box.kancloud.cn/2015-09-02_55e5d38568d3c.png" alt="IE" />Internet Explorer</th> <th class="type_firefox"><img src="https://box.kancloud.cn/2015-09-02_55e5d3857210f.png" alt="Firefox" />Firefox</th> <th class="type_chrome"><img src="https://box.kancloud.cn/2015-09-02_55e5d3857b4d9.png" alt="Chrome" />Chrome</th> <th class="type_opera"><img src="https://box.kancloud.cn/2015-09-02_55e5d3858296a.png" alt="Opera" />Opera</th> <th class="type_safari"><img src="https://box.kancloud.cn/2015-09-02_55e5d3858be47.png" alt="Safari" />Safari</th> </tr></thead><tbody><tr><td rowspan="4" class="version">版本</td> <td class="support no"><span>(×)</span>IE6</td> <td class="support yes"><span>(√)</span>Firefox 3.0.10</td> <td class="support yes"><span>(√)</span>Chrome 2.0.x</td> <td class="support yes"><span>(√)</span>Opera 9.64</td> <td class="support yes"><span>(√)</span>Safari 4</td> </tr><tr><td class="support no"><span>(×)</span>IE7</td> <td class="support yes"><span>(√)</span>Firefox 3.5</td> <td></td> <td></td> <td></td> </tr><tr><td class="support no"><span>(×)</span>IE8</td> <td></td> <td></td> <td></td> <td></td> </tr><tr><td></td> <td></td> <td></td> <td></td> <td></td> </tr></tbody></table>
### 示例:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" /><meta http-equiv="Content-Language" content="utf-8" /><meta name="robots" content="all" /><meta name="author" content="Tencent-ISRD" /><meta name="Copyright" content="Tencent" /><style>img.opacity1 { opacity:0.25;}img.opacity2 { opacity:0.50;}img.opacity3 { opacity:0.75;}</style><title>opacity</title></head><body><div><img src="http://imgcache.qq.com/ac/www_tencent/zh-cn/images/sitelogo_zh-cn.gif" class="opacity1" alt="tencent" /></div><div><img src="http://imgcache.qq.com/ac/www_tencent/zh-cn/images/sitelogo_zh-cn.gif" class="opacity2" alt="tencent" /></div><div><img src="http://imgcache.qq.com/ac/www_tencent/zh-cn/images/sitelogo_zh-cn.gif" class="opacity3" alt="tencent" /></div></body></html>
復制代碼
Copyright ? 2009 [Tencent ISD webteam](http://webteam.tencent.com/). All Rights Reserved
### 快速跳轉
- [語法](# "跳轉到“語法”")
- [取值](# "跳轉到“取值”")
- [說明](# "跳轉到“說明”")
- [兼容性](# "跳轉到“兼容性”")
- [示例](# "跳轉到“示例”")
- CSS3 Properties
- 邊框(Border)
- Border-color
- Border-image
- Border-radius
- box-shadow
- 背景(Background)
- background-origin
- background-clip
- Background-size
- Multiple backgrounds
- 顏色(Color)
- HSL colors
- HSLA colors
- opacity
- RGBA colors
- 文本(Text effects)
- text-shadow
- text-overflow
- word-wrap
- 用戶界面(User-interface)
- box-sizing
- resize
- outline
- outline-width
- outline-style
- outline-offset
- outline-color
- nav-index
- nav-up
- nav-right
- nav-down
- nav-left
- 基礎盒模型(Basic box model)
- overflow
- overflow-x
- overflow-y
- 內容(Generated Content)
- content
- 其它模塊(Other modules)
- media queries
- Speech
- columns
- column-width
- column-span
- column-rule
- column-rule-color
- column-rule-width
- column-rule-style
- column-gap
- column-fill
- column-count
- column-break-before
- column-break-after
- @font-face
- 選擇器(selectors)
- 子串匹配的屬性選擇符 E[att^="val"]
- 子串匹配的屬性選擇符 E[att$="val"]
- 子串匹配的屬性選擇符 E[att*="val"]
- 結構性偽類 E:root
- 結構性偽類 E:nth-child(n)
- 結構性偽類 E:nth-last-child(n)
- 結構性偽類 E:nth-of-type(n)
- 結構性偽類 E:nth-last-of-type(n)
- 結構性偽類 E:last-child
- 結構性偽類 E:first-of-type
- 結構性偽類 E:only-child
- 結構性偽類 E:only-of-type
- 結構性偽類 E:empty
- UI元素狀態偽類 E:checked
- UI元素狀態偽類 E:enabled
- UI元素狀態偽類 E:disabled
- UI元素狀態偽類 E::selection
- 否定偽類 E:not(s)
- 目標偽類 E:target
- 通用兄弟元素選擇器 E ~ F