How to overlay another div on one div, or how to overlay another div on one <img>

Create a wrapper div that wraps both divs and give the CSS position. If A is position: relative and B is in position: absolute, object B calculates top and left attribute values based on object A.

.item-wrapper {
    position: relative;
    /* Omitted */
}
.item-info-box {
    position: absolute;
    left: 0;
    bottom: 0.75em;
    /* The following is omitted */
}

See Demo.

+ If you're wondering "How did this implement the CSS?" right-click and click "Exam". You'll get a hint when the browser developer tool pops up.