CSS for background color opacity

Hi all, I'm having trouble changing the opacity of a heading background color in the custom CSS field.

I'm using the code below and thought the .5 in the final line would make opacity 50%. But it isn't working for some reason I can't figure out. 

#block-yui_3_17_2_1_1595131393232_6522 {
 padding-top: 20px;
background-color: #292b47; /* fallback for old browsers */
background-color:rgba 41, 43, 71, .5;
}

The attached screenshot is how the block renders.

Hi RWP, 

the rgba format is not working as suggested for some reason. And the opacity: 0.5 script applies to the whole box area, text and background. I want only the background color to be transparent.

Please post a link to your page.

It's not live yet, sorry. 

Set it up password protected and pm the password.

OK, tell me if you can't access this:

https://flute-penguin-hjsr.squarespace.com/

p/w: opacity20072020

You still have the syntax for rgba incorrect

#block-yui_3_17_2_1_1595131393232_6522 {
    padding-top: 20px;
    background-color: rgba(41,43,71,.5);
}

Aha, got it. thanks for your help!