Can a Single CSS Property Set Both Background Image and Opacity?

Setting Background Image and Opacity in a Single Property

Question:

Can I set a transparent background image using a single CSS property? If so, how?

Original Image Issue:

The provided image ("tandem.jpg") is too bright, so you'd like to reduce its opacity to around 0.2 while preserving its use as a background image.

Solution:

While there's no direct CSS property that allows you to set both the background image and opacity simultaneously, you can achieve the desired result using the following technique:

#main {
    position: relative;
}
#main:after {
    content : "";
    display: block;
    position: absolute;
    top: 0;
    left: 0;
    background-image: url(/wp-content/uploads/2010/11/tandem.jpg); 
    width: 100%;
    height: 100%;
    opacity : 0.2;
    z-index: -1;
}

Explanation:

• Create a new element (#main:after) as a child of the main element (#main). This element will be used to overlay the background image.
• Set its position to absolute so that it can be positioned relative to its parent element.
• Use the content property to set an empty string, effectively making this element invisible but allowing it to hold background styles.
• Set its opacity to 0.2 to achieve the desired transparency level for the background image.
• Set its z-index to -1 to ensure it appears behind the main element's content.

This technique effectively creates a transparent layer over the main element, showcasing the background image with the specified opacity.

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