Css Works in FF, doesn’t work in Opera and IE

[code]
div#left{
width:150px;
float:left;
border: 0.5px dashed black;
}

div#right{
width:150px;
float:right;
border: 0.5px dashed black;
}

div#main{
padding:15px;
margin: 0 150px;
border: 0.5px dashed black;
}

input{
margin:10px;
}

div.menu{
border: 0.5px dotted blue;
}
[/code]

Can someone tell me where’s the mistake? I have a simple webpage, but IE and Opera doesn’t show borders around divs…

Also in #CSS _↴