It is possible to do this, I just changed mine to 250px. I did it with the following changes:
style.css
#post-area .post {
width: 250px;
background: #FFF;
margin-right: 10px;
margin-top: 15px;
}
#post-area .post .pinbin-copy {
padding-top: 10px;
padding-bottom: 10px;
overflow: hidden;
clear: both;
width: 230px;
}
#post-area .post .pinbin-date {
width: 115px;
color: #8e8e8e;
font-size: 10px;
border-bottom: 1px dotted #cccccc;
padding-bottom: 0;
padding-top: 0;
}
#post-area .post .pinbin-link a {
text-decoration: none;
background: #444;
padding: 5px 10px;
color: #fafafa;
font-size: 12px;
float: right;
cursor: pointer;
position: absolute;
margin-left: 199px;
margin-top: -15px;
}
functions.php
add_theme_support( ‘post-thumbnails’ );
add_image_size(‘summary-image’, 251, 9999);
add_image_size(‘detail-image’, 750, 9999);