:: channels grumpy cat:: NO!
Opacity just doesnt work that way.
Am using percentages as a conceptual tool, not the actual value string.. hope you are able to follow my logic on this.
Consider it as a variable; if you give the container "50%" opacity, then '100%' opacity will calculate to 50%. Opacity, unlike font-size, cannot be greater than "100%" ( it wouldn't make sense anyway.. what's MORE THAN FULLY OPAQUE? )
That kinda leaves you with 3 choices:
1) a transparent PNG ( this is if you are looking for widest browser support)
2) the "transparency" you are trying to achieve is of a solid color, background: RGBA(r,g,b,a); works extremely well. Actually, for supporting browsers, this can be used for gradients as well.
3) If you MUST have a complex semi transparent BG, you could still use transparency ( see, it's not an entirely useless property) by using a pseudo element ( :before, :after),absolute position, and a negative z-index ( OR you could relative position the children and give THEM a higher z-index).
to get the pseudo element to cover the entire element , regardless of it's dimensions, use: top:0; bottom:0; left:0; right:0;
hope that helps