不透明度没有按预期工作

Question

我试图在 div 上设置不透明度，但它没有按预期工作。

https://jsfiddle.net/std0tgsy/1/

HTML

<div class="col-lg-offset-4 col-lg-3 col-md-6 col-sm-12 col-xs-12  haveaccount" style="opacity: 2;text-align: center;" >
  <h2>JOIN US AT START HERE, GO PLACES.</h2>
  <p>Sign up here, create your account, and we'll follow up with you to complete your profile. You'll 
  <br> have access to our tools  and can expect to receive some
  <br> freebies along the way, Welcome!</p>  

Answer 1

div {
    opacity: 0.5;
}

或

<div style="background-color:rgba(0, 0, 0, 0.5);">
   <div>
      Text added.
   </div>
</div>

http://www.w3schools.com/cssref/css3_pr_opacity.asp & https://css-tricks.com/almanac/properties/o/opacity/

Answer 2

<div style="opacity: 2"; >

加入我们，从这里开始，去往。

或

<h2 style="opacity:0.2">JOIN US AT START HERE, GO PLACES.</h2>

你也可以做外部 css 文件。

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