How to make transparent jpg background in css code example

Example 1: background color semi transparent

.transparent {
    background-color: rgba(255, 255, 255, 0.5);
}
.transparent {
    opacity: 0.5;
}

Example 2: css textarea background color transparent

textarea{
    width: 100%;
    color: #FFF;
    background: transparent;
    border: none;
    outline: none;
}