Transparent Footer (Opacity) not working

Hello,

i have a background image and i want to have the footer to have opacity (semi-transparent). i tryed this but the footer stays white. when i change the color to black and opacity like 0.5 the footer becomes grey (seems as somewhere the background color is white – but i cant find the css rule with google developer tools.).
try this but doesnt work:

#footer .containter, #footer{
    background: rgba(255,255, 255, 0.3) !important;
}

.footer_color {
background-color: rgba(255,255,255,.3);
}