Aireesan:*"rgba(0, 0, 0, 0.5)" not "rgb(0, 0, 0, 0.5)".
Transparent is the wrong word, you're looking for translucent. Transparent is entirely see-through whereas translucent is somewhat see-through.
You can achieve translucency with CSS by setting the background color to a RGB color that specifies the Alpha channel, which dictates how translucent the color is.
For a somewhat see-through black, use rgb(0,0,0,0.5)