当然，这不是css解决方案，但你可以使用CDN质子过滤器:

body {
    background: url('https://i0.wp.com/IMAGEURL?w=600&filter=blurgaussian&smooth=1');
}

它来自https://developer.wordpress.com/docs/photon/api/#filter

你所需要的只是“filter”:

blur(«WhatEverYouWantInPixels»);"

body { color: #fff; font-family: Helvetica, Arial, sans-serif; } #background { background-image: url('https://cdn2.geckoandfly.com/wp-content/uploads/2018/03/ios-11-3840x2160-4k-5k-beach-ocean-13655.jpg'); background-repeat: no-repeat; background-size: cover; width: 100vw; height: 100vh; overflow: hidden; position: absolute; top: 0; left: 0; z-index: -1; /* START */ /* START */ /* START */ /* START */ /* You can adjust the blur-radius as you'd like */ filter: blur(3px); } <div id="background"></div> <p id="randomContent">Lorem Ipsum</p>

正如在其他答案中所述，这可以通过以下方式实现:

作为背景的模糊图像的副本。 可以过滤的伪元素，然后将其定位在内容后面。

你也可以使用backdrop-filter

有一个受支持的属性叫做backdrop-filter，目前是 支持Chrome, Firefox, Edge, Safari和iOS Safari(查看caniuse.com统计数据)。

来自Mozilla devdocs:

backdrop-filter属性提供了一些效果，比如对元素后面的区域进行模糊或颜色移动，然后通过调整元素的透明度/不透明度就可以看到元素。

查看caniuse.com了解使用统计数据。

你会这样使用它。 如果你不想让里面的内容被模糊化，使用实用工具类.u-non- ambiguous

.background-filter::after { -webkit-backdrop-filter: blur(5px); /* Use for Safari 9+, Edge 17+ (not a mistake) and iOS Safari 9.2+ */ backdrop-filter: blur(5px); /* Supported in Chrome 76 */ content: ""; display: block; position: absolute; width: 100%; height: 100%; top: 0; } .background-filter { position: relative; } .background { background-image: url('https://upload.wikimedia.org/wikipedia/en/6/62/Kermit_the_Frog.jpg'); width: 200px; height: 200px; } /* Use for content that should not be blurred */ .u-non-blurred { position: relative; z-index: 1; } <div class="background background-filter"></div> <div class="background background-filter"> <h1 class="u-non-blurred">Kermit D. Frog</h1> </div>

pen

取消了对额外元素的需求，同时使内容适合文档流，而不是像其他解决方案那样固定/绝对。

通过使用

.content { /* this is needed or the background will be offset by a few pixels at the top */ overflow: auto; position: relative; } .content::before { content: ""; position: fixed; left: 0; right: 0; z-index: -1; display: block; background-image: url('https://i.imgur.com/lL6tQfy.png'); background-size:cover; width: 100%; height: 100%; -webkit-filter: blur(5px); -moz-filter: blur(5px); -o-filter: blur(5px); -ms-filter: blur(5px); filter: blur(5px); } <div class="content"> Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. </div>

编辑如果你想删除边缘的白色边框，使用宽度和高度为110%，左侧和顶部为-5%。这将放大你的背景-但不应该有纯色从边缘流出。感谢Chad Fawcett的建议。

.content { /* this is needed or the background will be offset by a few pixels at the top */ overflow: auto; position: relative; } .content::before { content: ""; position: fixed; top: -5%; left: -5%; right: -5%; z-index: -1; display: block; background-image: url('https://i.imgur.com/lL6tQfy.png'); background-size:cover; width: 110%; height: 110%; -webkit-filter: blur(5px); -moz-filter: blur(5px); -o-filter: blur(5px); -ms-filter: blur(5px); filter: blur(5px); } <div class="content"> Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. </div>

div { background: inherit; width: 250px; height: 350px; position: absolute; overflow: hidden; /* Adding overflow hidden */ } div:before { content: ‘’; width: 300px; height: 400px; background: inherit; position: absolute; left: -25px; /* Giving minus -25px left position */ right: 0; top: -25px; /* Giving minus -25px top position */ bottom: 0; box-shadow: inset 0 0 0 200px rgba(255, 255, 255, 0.3); filter: blur(10px); }

下面是一个简单的解决方案，适用于现代浏览器，使用纯CSS和一个'before'伪元素，就像Matthew Wilcoxson的解决方案一样。

为了避免在JavaScript中需要访问伪元素来更改图像和其他属性，只需使用inherit作为值，并通过父元素(这里是body)访问它们。

body::before {
    content: ""; /* Important */
    z-index: -1; /* Important */
    position: inherit;
    left: inherit;
    top: inherit;
    width: inherit;
    height: inherit;
    background-image: inherit;
    background-size: cover;
    filter: blur(8px);
}

body {
  background-image: url("xyz.jpg");
  background-size: 0 0;  /* Image should not be drawn here */
  width: 100%;
  height: 100%;
  position: fixed; /* Or absolute for scrollable backgrounds */
}