是否有可用的CSS规则可以删除之前在样式表中为特定元素设置的任何样式?
一个很好的例子可能是在一个移动优先的RWD站点中,在这个站点中,用于小屏幕视图中的特定元素的许多样式都需要“重置”或删除桌面视图中的相同元素。
一个CSS规则可以实现如下功能:
.element {
all: none;
}
使用示例:
/* mobile first */
.element {
margin: 0 10;
transform: translate3d(0, 0, 0);
z-index: 50;
display: block;
etc..
etc..
}
@media only screen and (min-width: 980px) {
.element {
all: none;
}
}
因此,我们可以快速删除或重新设置样式,而不必声明每个属性。
CSS属性all有一个关键字initial,它将CSS属性设置为规范中定义的初始值。all关键字有广泛的浏览器支持,除了IE和Opera Mini家族。
/* basic modern patch */
#reset-this-root {
all: unset;
}
or
#reset-this-root {
all: initial;
}
由于IE缺乏支持可能会导致问题,这里有一些方法可以重置一些CSS属性到它们的初始值:
.reset-this {
animation : none;
animation-delay : 0;
animation-direction : normal;
animation-duration : 0;
animation-fill-mode : none;
animation-iteration-count : 1;
animation-name : none;
animation-play-state : running;
animation-timing-function : ease;
backface-visibility : visible;
background : 0;
background-attachment : scroll;
background-clip : border-box;
background-color : transparent;
background-image : none;
background-origin : padding-box;
background-position : 0 0;
background-position-x : 0;
background-position-y : 0;
background-repeat : repeat;
background-size : auto auto;
border : 0;
border-style : none;
border-width : medium;
border-color : inherit;
border-bottom : 0;
border-bottom-color : inherit;
border-bottom-left-radius : 0;
border-bottom-right-radius : 0;
border-bottom-style : none;
border-bottom-width : medium;
border-collapse : separate;
border-image : none;
border-left : 0;
border-left-color : inherit;
border-left-style : none;
border-left-width : medium;
border-radius : 0;
border-right : 0;
border-right-color : inherit;
border-right-style : none;
border-right-width : medium;
border-spacing : 0;
border-top : 0;
border-top-color : inherit;
border-top-left-radius : 0;
border-top-right-radius : 0;
border-top-style : none;
border-top-width : medium;
bottom : auto;
box-shadow : none;
box-sizing : content-box;
caption-side : top;
clear : none;
clip : auto;
color : inherit;
columns : auto;
column-count : auto;
column-fill : balance;
column-gap : normal;
column-rule : medium none currentColor;
column-rule-color : currentColor;
column-rule-style : none;
column-rule-width : none;
column-span : 1;
column-width : auto;
content : normal;
counter-increment : none;
counter-reset : none;
cursor : auto;
direction : ltr;
display : inline;
empty-cells : show;
float : none;
font : normal;
font-family : inherit;
font-size : medium;
font-style : normal;
font-variant : normal;
font-weight : normal;
height : auto;
hyphens : none;
left : auto;
letter-spacing : normal;
line-height : normal;
list-style : none;
list-style-image : none;
list-style-position : outside;
list-style-type : disc;
margin : 0;
margin-bottom : 0;
margin-left : 0;
margin-right : 0;
margin-top : 0;
max-height : none;
max-width : none;
min-height : 0;
min-width : 0;
opacity : 1;
orphans : 0;
outline : 0;
outline-color : invert;
outline-style : none;
outline-width : medium;
overflow : visible;
overflow-x : visible;
overflow-y : visible;
padding : 0;
padding-bottom : 0;
padding-left : 0;
padding-right : 0;
padding-top : 0;
page-break-after : auto;
page-break-before : auto;
page-break-inside : auto;
perspective : none;
perspective-origin : 50% 50%;
position : static;
/* May need to alter quotes for different locales (e.g fr) */
quotes : '\201C' '\201D' '\2018' '\2019';
right : auto;
tab-size : 8;
table-layout : auto;
text-align : inherit;
text-align-last : auto;
text-decoration : none;
text-decoration-color : inherit;
text-decoration-line : none;
text-decoration-style : solid;
text-indent : 0;
text-shadow : none;
text-transform : none;
top : auto;
transform : none;
transform-style : flat;
transition : none;
transition-delay : 0s;
transition-duration : 0s;
transition-property : none;
transition-timing-function : ease;
unicode-bidi : normal;
vertical-align : baseline;
visibility : visible;
white-space : normal;
widows : 0;
width : auto;
word-spacing : normal;
z-index : auto;
/* basic modern patch */
all: initial;
all: unset;
}
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综上所述,我不认为CSS重置是可行的,除非我们最终只有一个web浏览器,如果'默认'是由浏览器设置的。
更好的解决方案
下载“复制/粘贴”样式表,将css属性重置为默认值(UA样式):
https://github.com/monmomo04/resetCss.git
Thanks@Milche Patern!
I was really looking for reset/default style properties value. My first try was to copy the computed value from the browser Dev tool of the root(html) element. But as it computed, it would have looked/worked different on every system.
For those who encounter a browser crash when trying to use the asterisk * to reset the style of the children elements, and as I knew it didn't work for you, I have replaced the asterisk "*" with all the HTML tags name instead. The browser didn't crash; I am on Chrome Version 46.0.2490.71 m.
At last, it's good to mention that those properties will reset the style to the default style of topest root element but not to the initial value for each HTML element. So to correct this, I have taken the "user-agent" styles of webkit based browser and implemented it under the "reset-this" class.
Useful link:
下载“复制/粘贴”样式表,将css属性重置为默认值(UA样式):
https://github.com/monmomo04/resetCss.git
用户代理风格:
浏览器默认的HTML元素CSS
http://trac.webkit.org/browser/trunk/Source/WebCore/css/html.css
Css的特殊性(注意特殊性):
https://css-tricks.com/specifics-on-css-specificity/
https://github.com/monmomo04/resetCss.git
如果你碰巧在构建系统中使用sass,一种在所有主流浏览器中都能工作的方法是用:not()选择器包装你所有的样式导入,就像这样…
:not(.disable-all-styles) {
@import 'my-sass-file';
@import 'my-other-sass-file';
}
然后你可以在容器上使用disable类,子内容不会有任何你的样式。
<div class="disable-all-styles">
<p>Nothing in this div is affected by my sass styles.</p>
</div>
当然,现在所有的样式都将以:not()选择器作为前缀,所以这有点难看,但效果很好。