<div id="mydiv">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="1">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="2">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="3">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="4">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="5">
<img width="190" height="190" src="http://distilleryimage0.s3.amazonaws.com/9fe1cfd2cd4311e28e5722000a9f195f_6.jpg" id="6">
</div>
<style>
div#mydiv img#1 {width:30px}
div#mydiv img#2 {width:60px}
</style>
スタイリングが上手くいかない理由とは?
JS フィドル: http://jsfiddle.net/FqrDR/1/