CSS max-width not working

css

Solution

You can set:

#wrapper {
    -webkit-box-sizing: border-box; /* Safari, other WebKit */
    -moz-box-sizing: border-box;    /* Firefox, other Gecko */
    box-sizing: border-box;         /* Opera/IE 8+ */

    width: 100%;
    max-width: 1200px;
    height: 100px;
    margin: 0 auto;
    border: 4px solid;
}

Problem

I have this code, but strangely the max-width and with property are not working: HTML: ``` <body> <img src="imgs/topBar.png"> <div id ="wrapper"> </div> </body> ``` CSS: ``` body { padding: 0; margin: 0; } body img:first-child{ width: 100%; height: 5px; margin:0; display: block; } #wrapper { width: 100%; max-width: 1200px; height: 100px; margin: 0 auto; border: 4px solid; } ``` I made a http://jsfiddle.net/vkdbq/

Original source