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<!DOCTYPE html>
<html>
<head>
<style>
:root {
  --blue: #1e90ff;
  --white: #ffffff; 
}
​
body {
  background-color: var(--blue);
}
​
h2 {
  border-bottom: 2px solid var(--blue);
}
​
.container {
  color: var(--blue);
  background-color: var(--white);
  padding: 15px;
}
​
button {
  --blue: #0000ff;
  background-color: var(--white);
  color: var(--blue);
  border: 1px solid var(--blue);
  padding: 5px;
}
</style>
</head>
<body>
​
<h1>用局部变量覆盖全局变量</h1>
​
<div class="container">
  <h2>Welcome to Shanghai!</h2>
  <p>Shanghai is one of the four direct-administered municipalities of the People's Republic of China.</p>
  <p>Shanghai is one of the four direct-administered municipalities of the People's Republic of China.</p>
  <p>
    <button>Yes</button>
    <button>No</button>
  </p>
</div>
​
</body>
</html>
​