html - 用另一张图片覆盖 body 背景

Question

我正试图用另一张图片覆盖 html 正文背景图片。我使用了 z-index 但无法正常工作。我是不是遗漏了什么，或者只是无法理解我在做什么。

参见下面的示例代码:

body, html {
    margin: 0;
    /* The image used */
    background-image: url('http://lorempixel.com/output/nature-q-c-1176-907-10.jpg');

    /* Full height */
    height: 100%; 

    /* Create the parallax scrolling effect */
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
}

#main-content {
    background-image: url('http://lorempixel.com/output/food-q-c-640-633-1.jpg');
    z-index: 10;
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    position: relative;
}

.content {
    /*height: 700px;*/
    height: 100vh;
    background:rgba(255,255,255,0.5);
    /*margin-top: 20%;*/
}

<div id="main-content">
  <div class="content">something in here..</div>
  <div class="content">something in here..</div>
  <div class="content">something in here..</div>
</div>

Additionaly, inside the main-content are divs with 100vh and background opacity

主要内容图像应该位于所有内容之上，包括背景不透明的 content div。

Answer 1

在#main-content 上使用100% 宽度和高度，例如:

#main-content {
  width: 100%;
  height: 100%;
}

看看下面的片段:

body, html {
    margin: 0;
    /* The image used */
    background-image: url('http://lorempixel.com/output/nature-q-c-1176-907-10.jpg');

    /* Full height */
    height: 100%; 

    /* Create the parallax scrolling effect */
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
}

#main-content {
    background-image: url('http://placehold.it/500x500');
    z-index: 10;
    background-attachment: fixed;
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    position: relative;
    width: 100%;
    height: 100%;
}

<div id="main-content"></div>

希望这对您有所帮助!