Take backup and open the file: /templates/ja_mica/css/template.css and find the following codes:
1) The main content ‘s width:
#ja-content {
clear: both;
display: block;
float: left;
width: 50%;
}
2) The left column’s width ( this column contains column 1 and column 2)
#ja-cols {
float: right;
overflow: hidden;
width: 50%;
}
3) The width of the column 1 and column 2
#ja-col1 {
clear: both;
float: left;
overflow: hidden;
width: 50%;
}
#ja-col1 .inner {
background: none;
margin: 0;
padding: 0 10px 0 0;
}
#ja-col2 {
float: right;
overflow: hidden;
width: 50%;
}
Now you can adjust the width values on those blocks, to your preference.