动画不工作 CSS

Question

我正在尝试为 CSS class 添加一些动画 这是代码：

#primary_nav_wrap li a:hover:after {
  height: 4px;
  -webkit-border-radius: 4px 4px 0 0;
  -moz-border-radius: 4px 4px 0 0;
  border-radius: 4px 4px 0 0;
  background-color: #23a298;
  bottom: 0;
  content: "";
  left: 0;
  right:0;
  margin-left:auto;
  margin-right:auto;
  position: absolute;
  top: 96px;
  width: calc(100% - 15px);

  -webkit-transition: color 0.4s ease-out;
  -moz-transition: color 0.4s ease-out;
  -o-transition: color 0.4s ease-out;
  -ms-transition: color 0.4s ease-out;
  transition: color 0.4s ease-out;
}

一切都很好，但是这部分不起作用：

-webkit-transition: color 0.4s ease-out;
-moz-transition: color 0.4s ease-out;
-o-transition: color 0.4s ease-out;
-ms-transition: color 0.4s ease-out;
transition: color 0.4s ease-out;

Answer 1

尝试在没有应用悬停的情况下在元素上放置过渡：

#primary_nav_wrap li a:after {
    -webkit-transition: color 0.4s ease-out;
    -moz-transition: color 0.4s ease-out;
    -o-transition: color 0.4s ease-out;
    -ms-transition: color 0.4s ease-out;
    transition: color 0.4s ease-out;
}

编辑：您正在更改 a 标签上的颜色，因此您需要在那里应用过渡。

#primary_nav_wrap ul a {
    -webkit-transition: color 0.4s ease-out;
    -moz-transition: color 0.4s ease-out;
    -o-transition: color 0.4s ease-out;
    -ms-transition: color 0.4s ease-out;
    transition: color 0.4s ease-out;
}

See jsfiddle here.

Answer 2

将此代码添加到您的 a:after

#primary_nav_wrap li a:after {
  height: 4px;
  -webkit-border-radius: 4px 4px 0 0;
  -moz-border-radius: 4px 4px 0 0;
  border-radius: 4px 4px 0 0;
  bottom: 0;
  content: "";
  left: 0;
  right: 0;
  margin-left: auto;
  margin-right: auto;
  position: absolute;
  top: 96px;
  width: calc(100% - 15px);
  -webkit-transition: background-color 0.4s ease-out;
  -moz-transition: background-color 0.4s ease-out;
  -o-transition: background-color 0.4s ease-out;
  -ms-transition: background-color 0.4s ease-out;
  transition: background-color 0.4s ease-out;
}

你没有把过渡效果放在悬停上，而且，你没有提到应该使用哪种样式进行过渡，所以我把它给了 background-color

示例：

https://jsfiddle.net/7o2mw6ng/