How to put an image over another bigger image, like on youtube, a play button is displayed on top of video thumbnail?
I'm not sure that YouTube uses images for this effect, isn't it still the Flash player?
Anyhow, exactly how this is done depends very much on the design you want to achieve. Lets assume that you want to achieve the YouTube style, where you have a thumbnail image and want to overlay a play button image on top. If you want the thumbnail to be an actual tag you will need some extra markup, like this:
The wrapper (I haven't actually tested this, if its blatently wrong let me know I'll revise it!) This assumes a couple of things: You could also use the If you have other requirements it might be possible to do this without the extra markup, as I said it all depends on what you need exactly. Some requirements may not be possible without JavaScript (which would of course mean you could inject any extra markup with that!)..thumb-wrapper {
position:relative;
}
.thumbwrapper span {
position:absolute;
top: 0px;
left: 0px;
width: 100%;
height: 100%;
z-index: 100;
background: transparent url(overlay.png) no-repeat;
}
opacity: style to achieve #2. Of course, IE6 will rear it's ugly head and you'll need to use a PNG fix for it if going the transparent image route, or a separate opacity filter if using that method. Both of these are undoubtadly answered elsewhere on Stack Overflow or easily google-able.