backgroud:#333;
background: rgb(0,0,0,0,7);

What is the best value define for “Alfa” in rgba(). Because I always use this Alfa coordinate as decimal(0.1 – 0.9), as transparency declare in rgba(). I know it also have value from “1-255”. But if we want to define a color as simple rgb() is always equal to rgba() if we declare “Alfa” from “1-255”, Please tell me .

You can overwrite the alpha value on :hover by writing out the CSS property again with the same color and new alpha value.

div{
    background-color: rgba(0,0,0,1);
}
div:hover{
    background-color: rgba(0,0,0,0.7);
}