Inventory doesn't support transparent colors, only RGB

I can't make a resourse pack with a inventroy that uses transparent colors only rbg, So now i have to have an extremly ugly inventory in my texturepack. I think Mojang should realy fix this because it's blocking my creativity!

This is how it should look

And this is not how it should look. the lines and the boxes are suppose to look like my hotbar, but i changed it because it was so ugly just black!