Left Sidebar Menu Cant Change Width

I am using the travel blogger theme v. 1.3.5 and the single left sidebar option and wish to reduce the width of the left sidebar menu. I read several forums and they advised to reduce the width of the under the sidebar section in style.css. So the section I changed was
.widget-listing img {
float: left;
margin:6px 8px 10px 0;
max-width: 45px;
I reduced the max-width from 60px to 45px. I also increased the width of the main body by 15px and neither effected the look of the site in any way.

I also tried several other things but could not reduce the width. Could someone please assist.

This is my first ever post so forgive me if I do something incorrect.

Thanks
Dave