在背景图片之上有一个透明的 box/overlay

Question

我有这张图片 (https://cdn.pixabay.com/photo/2015/08/25/03/51/toner-906142__480.jpg) 作为背景图片，下面有这个灯箱。我希望将灯箱放在背景图像的顶部，以便可以通过灯箱看到背景图像。我试图进入图片（顶部）而不是在图片之外，但到目前为止没有任何效果。

我想把这个标题和这些词放在白框里，背景图像是低谷的（不透明度大概是 0.5）。

        <h2 style="color: black" align="center">Food is essential part of our well-being</h2> 
        <p>Our expertise </p>

这里是 bootstrap/HTML.

<!doctype html>
<html lang="en">
  <head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">
<link rel="stylesheet" href="style.css">
    <title>Hello, world!</title>
  </head>
  <body>

    <nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="instagram" href="#">
  <img src="https://cdn3.iconfinder.com/data/icons/picons-social/57/38-instagram-256.png" width="35" height="35" alt=""></a>
    <a class="facebook" href="#">
  <img src="https://cdn3.iconfinder.com/data/icons/wpzoom-developer-icon-set/500/01-256.png" width="35" height="35" alt=""></a>
      <a class="twitter" href="#">
  <img src="https://cdn2.iconfinder.com/data/icons/font-awesome/1792/twitter-square-256.png" width="35" height="35" alt=""></a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#experts">Our experts <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item active">
        <a class="nav-link" href="#service">Our service <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item active">
        <a class="nav-link" href="#food">Food <span class="sr-only">(current)</span></a>
      </li>
        <li class="nav-item active">
        <a class="nav-link" href="#contact">Contact <span class="sr-only">(current)</span></a>
      </li>
      <!-- <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li> -->

    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>
    <script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>

      <div class="container" href="service"> 
     <img src="https://cdn.pixabay.com/photo/2015/08/25/03/51/toner-906142__480.jpg" id="ourservicepicture"> 
     <div class="transbox">
        <h2 style="color: black" align="center">Food is essential part of our well-being</h2> 
        <p>Our expertise </p>
 </div>


     </div>
    </div> 
  </body>
</html>

和CSS：

h1{

}

#h1{
    color:blue;
    padding-bottom:30px;
    font-family: CelebriSans;
}

h2{
    font-family: CelebriSans;
    margin-top:10px;
}

.navbar{
background-color:#c99ab1 !important;
height:11%;
}

.main{
    height:60%;
    width:100%;
    grid-row: 1/4;
}

p{
font-family: CelebriSans;
font-size:16px; 
font-style:bold;
}

div.container{
  /* The image used */
  /* background-image: url("https://cdn.pixabay.com/photo/2015/08/25/03/51/toner-906142__480.jpg");  */
  position: relative; 
  max-width:100%;

  /* Full height */
  height: 100%;
  margin: 0 auto; /* Center it */

  /* Center and scale the image nicely */
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

/*
.container .content{
  position: absolute;
  /* background: rgb(0, 0, 0); /* Fallback color */  
  /*background: rgba(255,255,255, 0.5); /* White background with 0.5 opacity 
  color: black;
  width: 75%;
  padding: 20px;

}
*/

#ourservicepicture{
    height:100%;
    width:100%;
    margin:0px;
    margin-left:0px;
    margin-right:0px;
}



div.transbox {

margin: 30px;

background-color: #ffffff;

border: 1px solid black;

opacity: 0.6;

filter: alpha(opacity=60); /* For IE8 and earlier */



}

div.transbox p {

margin: 5%;

font-weight: bold;

font-family: Verdana;

font-size: 12px;

color: #000000;

}

Answer 1

只需将此 CSS 添加到您的 .transbox 样式中

https://jsfiddle.net/rjaw5nvx/

position: absolute;
top: 50%;
transform: translateY(-50%);

您也可以使用 flexbox 使盒子垂直和水平居中，但这有点复杂。

Answer 2

您可以在 .container 上使用 display: flex 将 .container 内的元素放在顶部。我添加了一些注释以最小化您的代码。看看吧！

.container {
  background-image: url("https://cdn.pixabay.com/photo/2015/08/25/03/51/toner-906142__480.jpg");
  /* Add the background image like this */
  height: 500px;
  /* Give the background image the correct height */
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
  display: flex;
  /* Places content inside on top */
  justify-content: center;
  /* Center horizontally */
  align-items: center;
  /* Center vertically */
}

.transbox {
  padding: 30px;
  background-color: rgba(255, 255, 255, 0.5);
  /* Opacity can be given to background with rgba*/
  border: 1px solid black;
  height: 100px;
}

<div class="container" href="service">
  <div class="transbox">
    <h2>
      Food is essential part of our well-being
    </h2>
    <p>Our expertise </p>
  </div>
</div>

在背景图片之上有一个透明的 box/overlay

Having a transparent box/overlay on top of the backround image

html

css

transparent

background-image

opacity