CSS Transparency Settings for All Browsers | CSS-Tricks: "Transparency is one of those CSS properties that has a weird history and requires lots of different properties and values to ensure cross browser compatibility that goes back as far as you can. To cover all your bases, you need a bunch of CSS statements. Fortunately they don't interfere with each other, so using them all every time you wish to add transparency is no big hassle and worry-free. Here they are, and are currently set to 50% transparency:"
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