[Wordpress issuses] sharonshero on "How do I make the container semi-transparent in Twenty-Twelve?"

apply the following CSS:

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

Pay attention to the numbers in bold. The first three numbers are the RGB color for white (in other words, all three colors, Red, Green, and Blue, are set to maximum, which equals white).

The last number is the opacity, with 0 being fully transparent, and 1 being fully opaque. You can adjust the 0.8 up or down until you find a level that lets you show the background image through while still being legible.

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