In your subsequent stylesheet 'screen.css', there's a rule:
.resume img { margin-bottom:-30px; }
which is overriding your img.portrait rule from 'base.css'. You can either remove the rule from 'screen.css', or change the rule in 'base.css' to:
img.portrait
{float: left;
margin: 0 25px 25px 10px !important;
width: 300px;
height: auto;
border: 3px solid #666;
}
You should generally avoid using '!important' because it can make your CSS very convoluted and difficult to maintain.