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How do I give text or an image a transparent background using CSS? 26 answers

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Use rgba :

.dropdown .dropdown-menu {
    background-color: rgba(255, 255, 255, 0.8);
}

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From the documentation:

rgba()

Colors can be defined in the Red-green-blue-alpha model (RGBa) using the rgba() functional notation. RGBa extends the RGB color model to include the alpha channel, allowing specification of the opacity of a color. a means opacity: 0=transparent; 1=opaque;

rgba(255,0,0,0.1) /* 10% opaque red */

rgba(255,0,0,0.4) /* 40% opaque red */

rgba(255,0,0,0.7) /* 70% opaque red */

rgba(255,0,0, 1) /* full opaque red */

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在你的CSS上进行以下更改

.dropdown .dropdown-menu {
    background-color: rgba(255,255,255,0.5);
}

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