CSS currentColor 变量的使用

html {
  color: red;
  animation: color 30s linear infinite;
}

@keyframes color {
  33.3% { color: #0f0; }
  66.7% { color: #00f; }
}


body {
  font-family: sans-serif;
  margin: 2em;
  border-top: 2px solid;
  position: relative;
  padding: 1em;
}

body:before {
  content: "";
  position: absolute;
  display: block;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  opacity: .1;
  background-color: currentColor;
  background-image: linear-gradient(to bottom, currentColor, #fff);
}

p, h1 {
  color: black;
  margin-top: 0;
}

button {
  color: inherit;
  display: block;
  text-decoration: none;
  padding: .5em 1em;
  background: white;
  border: 2px solid;
  margin: 0 auto;
  border-radius: .5em;
  box-shadow: 2px 2px;
  font-weight: bold;
}

<h1>Using currentColor for fun and profit</h1>
<p>In pure CSS you can use <code>currentColor</code> wherever you migth use a normal color value. This maps to whatever the current value of color is.</p>
<p>Go ahead, stick <code>currentColor</code> in gradients and backgrounds. It’s already the default for text, borders, and drop shadows so you don’t even need to define current color there.</p>

<button>Foobar</button>