去除文本的不透明度

Question

我有以下代码，并为纯色叠加颜色添加了不透明度。问题是文本也在使用不透明度。如何更改它以使文本没有不透明度并位于顶部？

.container {
  position: relative;
  width: 50%;
}

.image {
  display: block;
  width: 100%;
  height: auto;
}

.overlay {
  position: absolute;
  bottom: 100%;
  left: 0;
  right: 0;
  background-color: #008CBA;
  opacity: .5;
  overflow: hidden;
  width: 100%;
  height: 0;
  transition: .5s ease;
}

.container:hover .overlay {
  bottom: 0;
  height: 100%;
}

.text {
  color: white;
  font-size: 20px;
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  text-align: center;
}

<div class="container">
  <img src="https://cdn.searchenginejournal.com/wp-content/uploads/2019/07/the-essential-guide-to-using-images-legally-online-1520x800.png" class="image">
  <div class="overlay">
    <div class="text">Hello World</div>
  </div>
</div>

谢谢约翰

Answer 1

使用 RGBA 配色方案代替不透明度

RGB: #RRGGBBAA，而 A 是 alpha。你也可以使用rgba(r,g,b,a)

.container {
  position: relative;
  width: 50%;
}

.image {
  display: block;
  width: 100%;
  height: auto;
}

.overlay {
  position: absolute;
  bottom: 100%;
  left: 0;
  right: 0;
  background-color: #008CBA99; /* Instead of #008CBA */
  overflow: hidden;
  width: 100%;
  height:0;
  transition: .5s ease;
}

.container:hover .overlay {
  bottom: 0;
  height: 100%;
}

.text {
  color: white;
  font-size: 20px;
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  text-align: center;
}

<div class="container">
  <img src="https://cdn.searchenginejournal.com/wp-content/uploads/2019/07/the-essential-guide-to-using-images-legally-online-1520x800.png" class="image">
  <div class="overlay">
    <div class="text">Hello World</div>
  </div>
</div>