Resize <img/> using absolute positioning - css

Question

div#ipsko changes width and height to satisfy absolute positioning.
Why img#utas doesn't?
JSFiddle: http://jsfiddle.net/pejh7/1/
HTML code:
<div id="upsko">
<img id="utas" src="http://kharg.czystybeton.pl/108.png" />
<div id="ipsko"></div>
</div>
CSS code:
div#upsko {
position: relative;
top: 200px; left: 200px; width: 100px; height: 100px;
background: rgba(255,0,0,0.5);
}
img#utas {
position: absolute;
top: 10px; left: 10px; right: 10px; bottom: 10px;
}
div#ipsko {
position: absolute;
top: 0; left: 0; bottom: 0; right: 0;
background: rgba(0,255,0,0.5);
}

Answer 1

Put the img tag in a div, give the image 100% width and height, and then absolute position the container div, e.g.
HTML:
<div id="upsko">
<div id="utas">
<img src="http://kharg.czystybeton.pl/108.png" />
</div>
<div id="ipsko"></div>
</div>
CSS:
#upsko {
position: relative;
top: 200px; left: 200px; width: 100px; height: 100px;
background: rgba(255,0,0,0.5);
}
#utas {
position: absolute;
top: 10px; left: 10px; right: 10px; bottom: 10px;
}
#utas img { height: 100%; width: 100%; }
#ipsko {
position: absolute;
top: 0; left: 0; bottom: 0; right: 0;
background: rgba(0,255,0,0.5);
}
Fiddle
The issues you describe are cause by the image width being unspecified (as other answers have stated) unfortunately without stating a px value for the image size (or converting the top/left/bottom/right and height+width to %) there's no way around this without adding an extra div.
I know adding extra div's is generally considered bad practice, but when it gives you flexibility as above, I think it's generally fine to do.

Answer 2

see the the div "div#ipsko" does not has its own height and width so it inherit its parent height and width . But the image has its own height and width . so you have to specify the height and width of image to make in fit in the div.
img#utas {
position: absolute;
top: 0px;
left: 0px;
right: 0px;
bottom: 0px;
width: 100%;
height: 100%;
}

Answer 3

div#upsko {
position: relative;
top: 20px;
left: 20px;
width: 100px;
height: 100px;
background: rgba(255,0,0,0.5);
}
img#utas {
position: absolute;
top: 0px;
left: 0px;
right: 0px;
bottom: 0px;
width: 100%;
height: 100%;
}
iv#ipsko {
position: absolute;
top: 0;
left: 0;
bottom: 0;
right: 0;
background: rgba(0,255,0,0.5);
}
please try above code.

Answer 4

You image's actual width and height are overriding things. (The browser will adjust an img element's dimensions to match that of the actual image, once it's downloaded it and can tell what they are, if no width and height are specified as attributes of the img or in the CSS.)
With a normal div rather than an image, you could reset the width and height back to auto if they were being set somewhere else, but auto for an image takes you back to the actual image dimensions. If you just wanted the image to match the size of the container, a 100% width/height would fix things, but that's not going to work if you want a different size implied by fixed positioning.
The only thing I can think of would be to change the markup so that your image loads inside a div, and then has 100% width.
Example jsFiddle here:
<div id="container">
<img id="utas" src="http://kharg.czystybeton.pl/108.png" />
</div>
div#container {
position: absolute;
top: 10px;
left: 10px;
right: 10px;
bottom: 10px;
width: auto;
height: auto;
}
img#utas {
width: 100%;
height: 100%;
}