:after Not displayed, why?

Question

css

#blcus {
    background-attachment: fixed;
    background-image: url(../images/b-h.jpg);
    background-size: cover;
    margin: 10px 30px 0px 30px;
    padding-bottom: 20px;
    position: relative;
    z-index: 1;
}
#blcus:after {
    background-color: #272a33f2;
    content: '';
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
    z-index: 2;
}

Hello. I'm doing a project and I have a problem with displaying :after...
Change has a section block, it has a background-image image and :after on top, which adds a dark color on top. Everything is written as it should, it is displayed for me personally, but the problem is that it is not displayed for other people and on phones, this after is, as it were, but the color value is not applied, what should I do?

Answer 1

In the 'background-color' property, shorten the value to 6 characters after '#', and at the same time add a second colon before 'after'

Answer 2

:after literally means after content
if there is no content in the block (empty) then after will not work
, so it does not work for images, inputs, etc.