How to make div appear in front of another?

You can set the z-index in css

<div style="z-index: -1"></div>

Use the CSS z-index property. Elements with a greater z-index value are positioned in front of elements with smaller z-index values.

Note that for this to work, you also need to set a position style (position:absolute, position:relative, or position:fixed) on both/all of the elements you want to order.