How to Change a CSS Background Image’s Opacity

With CSS and CSS3 you can do a lot of things, but setting an opacity on a CSS background is not one of them. However, if you get creative, there are a ton of creative work-arounds you to make it seem like you’re changing the CSS background image’s opacity. Both of the following methods have excellent browser support down to Internet Explorer 8.

Method 1: Use absolute positioning and an image

This method is exactly like it sounds. You simply use absolute positioning on an a normal img tag and make it seem like you used the CSS background-image property. All you have to do is put the image inside of a position: relative; container. Here’s what the HTML markup generally looks like:

<div class="my-container">
    <h1>Scotch Scotch Scotch</h1>
    <img src="http://placekitten.com/1500/1000">
</div>

And here’s what your CSS will look like:

.my-container {
    position: relative;
    overflow: hidden;
}
.my-container h1 {
    padding: 200px;
    position: relative;
    z-index: 2;
}
.my-container img {
    position: absolute;
    left: 0;
    top: 0;
    awidth: 100%;
    height: auto;
    opacity: 0.6;
}

Finally, here’s a nice little demo on CodePen: http://codepen.io/ncerminara/pen/tncAi

Method 2: Using CSS Pseudo-Elements

This method is seems simple once you see it, and is definitely my preferred method of doing this. Using CSS pseudo-elements of either :before or :after, you a div with a background image and set an opacity on it. Here’s what your HTML markup would roughly look like:

<div class="my-container">
    <h1>Scotch Scotch Scotch</h1>
</div>

And here’s what the CSS looks like:

.my-container {
    position: relative;
    background: #5C97FF;
    overflow: hidden;
}
/* You could use :after - it doesn't really matter */
.my-container:before {
    content: ' ';
    display: block;
    position: absolute;
    left: 0;
    top: 0;
    awidth: 100%;
    height: 100%;
    z-index: 1;
    opacity: 0.6;
    background-image: url('http://placekitten.com/1500/1000');
    background-repeat: no-repeat;
    background-position: 50% 0;
    -ms-background-size: cover;
    -o-background-size: cover;
    -moz-background-size: cover;
    -webkit-background-size: cover;
    background-size: cover;
}

Finally, here’s a nice little demo of this method:

data-theme-id=”0″ data-slug-hash=”eFzJI” data-default-tab=”result” data-user=”ncerminara” class=’codepen’> See the Pen How to Change a CSS Background Image’s Opacity by Nicholas Cerminara (@ncerminara) on CodePen.

https://scotch.io/tutorials/how-to-change-a-css-background-images-opacity