<div><p>CSS简写就是指将多行的CSS属性简写成一行，又称为CSS代码优化或CSS缩写。CSS简写的最大好处就是能够显著减少CSS文件的大小，优化网站整体性能，更加容易阅读。</p><p>下面介绍常见的CSS简写规则：</p><div style="page-break-after: always;"><span style="display: none;"><!--more-->& nbsp ;</span></div><h4>一、盒子大小</h4><p>这里主要用于两个属性：margin和padding，我们以margin为例，padding与之相同。盒子有上下左右四个方向，每个方向都有个外边距：</p><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> </td> <td> <div> <div>margin-top:1px;</div> <div>margin-right:2px;</div> <div>margin-bottom:3px;</div> <div>margin-left:4px;</div> </div> </td> </tr> </tbody></table><pre> </pre><p>你可以简写成：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>margin:1px2px3px4px;</div> </div> </td> </tr> </tbody></table><p>语法 margin:top right bottom left;</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> <div>7</div> <div>8</div> </td> <td> <div> <div>//四个方向的边距相同，等同于margin:1px1px1px1px;</div> <div>margin:1px;</div> <div>//上下边距都为1px，左右边距均为2px，等同于margin:1px2px1px2px;</div> <div>margin:1px2px;</div> <div>//右边距和左边距相同，等同于margin:1px2px3px2px;</div> <div>margin:1px2px3px;</div> <div>//注意，这里虽然上下边距都为1px，但是这里不能缩写。</div> <div>margin:1px2px1px3px;</div> </div> </td> </tr> </tbody></table><p>二、边框(border)</p><p>边框的属性如下：</p><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> </td> <td> <div> <div>border-width:1px;</div> <div>border-style:solid;</div> <div>border-color:#000;</div> </div> </td> </tr> </tbody></table><pre> </pre><p>可以缩写为一句：</p><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>border:1pxsolid#000;</div> </div> </td> </tr> </tbody></table><p>语法 border:width style color;</p><h4>三、背景(Backgrounds)</h4><p>背景的属性如下：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> </td> <td> <div> <div>background-color:#f00;</div> <div>background-image:url(background.gif);</div> <div>background-repeat:no-repeat;</div> <div>background-attachment:fixed;</div> <div>background-position:00;</div> </div> </td> </tr> </tbody></table><p>可以缩写为一句：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>background:#f00url(background.gif) no-repeatfixed00;</div> </div> </td> </tr> </tbody></table><p>语法是background:color image repeat attachment position;
你可以省略其中一个或多个属性值，如果省略，该属性值将用浏览器默认值，默认值为：</p><ul> <li> <p>color: transparent</p> </li> <li> <p>image: none</p> </li> <li> <p>repeat: repeat</p> </li> <li> <p>attachment: scroll</p> </li> <li> <p>position: 0% 0%</p> </li></ul><h4>四、字体(fonts)</h4><p>字体的属性如下：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> </td> <td> <div> <div>font-style:italic;</div> <div>font-variant:small-caps;</div> <div>font-weight:bold;font-size:1em;</div> <div>line-height:140%;</div> <div>font-family:"Lucida Grande",sans-serif;</div> </div> </td> </tr> </tbody></table><p>可以缩写为一句：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>font:italicsmall-capsbold1em/140%"Lucida Grande",sans-serif;</div> </div> </td> </tr> </tbody></table><p>注意，如果你缩写字体定义，至少要定义font-size和font-family两个值。</p><h4>五、列表(lists)</h4><p>取消默认的圆点和序号可以这样写list-style:none;,
list的属性如下:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> </td> <td> <div> <div>list-style-type:square;</div> <div>list-style-position:inside;</div> <div>list-style-image:url(image.gif);</div> </div> </td> </tr> </tbody></table><p>可以缩写为一句：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>list-style:squareinsideurl(image.gif);</div> </div> </td> </tr> </tbody></table><p>六、颜色(Color)</p><p>16进制的色彩值，如果每两位的值相同，可以缩写一半。例如：</p><p>Aqua: #00ffff ——#0ff
Black: #000000 ——#000
Blue: #0000ff ——#00f
Dark Grey: #666666 ——#666
Fuchsia:#ff00ff ——#f0f
Light Grey: #cccccc ——#ccc
Lime: #00ff00 ——#0f0
Orange: #ff6600 ——#f60
Red: #ff0000 ——#f00
White: #ffffff ——#fff
Yellow: #ffff00 ——#ff0</p><h4>七、属性值为0</h4><p>书写原则是如果CSS属性值为0，那么你不必为其添加单位(如:px/em)，你可能会这样写:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>padding:10px5px0px0px;</div> </div> </td> </tr> </tbody></table><p>试试这样吧:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> </td> <td> <div> <div>padding:10px5px00;</div> </div> </td> </tr> </tbody></table><p>八、最后一个分号</p><p>最后一个属性值后面分号可以不写，如：</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> </td> <td> <div> <div>#nav{</div> <div>border-top:4pxsolid#333;</div> <div>font-style: normal;</div> <div>font-variant:normal;</div> <div>font-weight: normal;</div> <div>}</div> </div> </td> </tr> </tbody></table><p>可以简写成:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> </td> <td> <div> <div>#nav{</div> <div>border-top:4pxsolid#333;</div> <div>font-style: normal;</div> <div>font-variant:normal;</div> <div>font-weight: normal</div> <div>}</div> </div> </td> </tr> </tbody></table><p>九、字体粗细(font-weight)</p><p>你可能会这样写:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> </td> <td> <div> <div>h1{</div> <div>font-weight:bold;</div> <div>}</div> <div>p{</div> <div>font-weight:normal;</div> <div>}</div> </div> </td> </tr> </tbody></table><p>可以简写成:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> </td> <td> <div> <div>h1{</div> <div>font-weight:700;</div> <div>}</div> <div>p{</div> <div>font-weight:400;</div> <div>}</div> </div> </td> </tr> </tbody></table><h4>十、圆角半径(border-radius)</h4><p>border-radius是css3中新加入的属性，用来实现圆角边框。</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> <div>4</div> <div>5</div> <div>6</div> <div>7</div> <div>8</div> <div>9</div> </td> <td> <div> <div>-moz-border-radius-bottomleft:6px;</div> <div>-moz-border-radius-topleft:6px;</div> <div>-moz-border-radius-topright:6px;</div> <div>-webkit-border-bottom-left-radius:6px;</div> <div>-webkit-border-top-left-radius:6px;</div> <div>-webkit-border-top-right-radius:6px;</div> <div>border-bottom-left-radius:6px;</div> <div>border-top-left-radius:6px;</div> <div>border-top-right-radius:6px;</div> </div> </td> </tr> </tbody></table><p>可以简写成:</p><pre> </pre><table border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td> <div>1</div> <div>2</div> <div>3</div> </td> <td> <div> <div>-moz-border-radius:06px6px;</div> <div>-webkit-border-radius:06px6px;</div> <div>border-radius:06px6px;</div> </div> </td> </tr> </tbody></table><p>语法 border-radius:topleft topright bottomright bottomleft</p></div>