如何从这个css类选择器声明中去掉冗余？

Question

我有：

    .sketch_img_thumb_box .title{
      opacity: 0.1;
    }
    .sketch_img_thumb_box:hover .title{
      opacity: 1;
    }

    .sketch_img_thumb_box .artist{
      opacity: 0.1;
    }
    .sketch_img_thumb_box:hover .artist{
      opacity: 1;
    }


    .sketch_img_thumb_box .rating_bar {
      opacity: 0.1;
    }
    .sketch_img_thumb_box:hover .rating_bar  {
      opacity: 1;
    }

我把它写成：

  .sketch_img_thumb_box .title, .sketch_img_thumb_box .artist, .sketch_img_thumb_box .rating_bar{
     opacity: 0.1;
 }
  .sketch_img_thumb_box:hover .title, .sketch_img_thumb_box:hover .artist,   .sketch_img_thumb_box:hover .rating_bar{
    opacity: 1;
}

我们还能进一步优化吗？

Answer 1

像这样写

css：

.sketch_img_thumb_box{
         opacity: 0.1;
     }
    .sketch_img_thumb_box:hover{
         opacity: 1;
     }

html：

<div class="sketch_img_thumb_box">
  <div class="title"></div>
  <div class="artist"></div>
  <div class="rating_bar"></div>
</div>

因为如果你给opacity parent，那么children会自动得到不透明度。

检查fiddle http://jsfiddle.net/sandeep/axuxT/4/

如果还有您不想给opacity的其他children，请编写以下代码：

.no_bar{width:50px;height:50px;margin:5px;}
.sketch_img_thumb_box > *{opacity:0.1;display:inline-block;}
.sketch_img_thumb_box:hover > *{opacity:1}
.no_bar{background:black;opacity:1}

检查fiddle http://jsfiddle.net/sandeep/RqP6p/