Custom CSS Not Loading

I have added some CSS to make my blog post background semi-transparent. It looks great when I have the Design tab open but doesn't show up after the page has been refreshed or if I open my site in a new webpage. The weird part is that it fixes itself every time I reopen the Design tab.

Here's the CSS I added:

Here is what it should look like:

Here is what it actually looks like:

You can view my website here: https://lion-wedge-b4fc.squarespace.com/ password is 12494

I see this code when inspecting element, there is a space after f0f0f0, so it didn't work

#block-f4b2353168eee1f9c26d {
    background: #f0f0f0 99 !important;
    padding: 50px
}

it should be

#block-f4b2353168eee1f9c26d {
    background: #f0f0f099 !important;
    padding: 50px;
}

Strange that there's a space there when you inspect. Since I couldn't take out a space that's not there, I just changed the color code to rgb and that did the trick. 👍