html - 为什么这个链接悬停效果是从中间开始而不是左边呢？

Question

我不明白为什么在下面的代码中，链接悬停效果从中间开始，而不是从左到右。有人可以解释为什么会这样吗？

.orange-link {
  color: orange;
  position: relative;
  text-decoration: none;
}

.orange-link:before {
  content: "";
  position: absolute;
  width: 100%;
  height: 3px;
  background: orange;
  bottom: 0;
  border-radius: 5px;
  transform: scaleX(0);
  transition: .25s linear;
}

.orange-link:hover:before,
.orange-link:focus:before {
  transform: scaleX(1);
}

<p>Visit the official rules <a class="orange-link" href="#">here</a> on how to send in a write-in entry.</p>

Answer 1

这是因为 CSS 转换的默认原点是元素的中心。

"By default it is at the center of the element and can be moved. It is used by several transforms, like rotations, scaling or skewing, that need a specific point as a parameter." — https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Transforms/Using_CSS_transforms

线条横跨整个宽度，但缩放到 0(从中心开始)。然后，悬停时，线条会按比例缩小到原来的全宽。