Child Theme not affecting layout

Hi,

I currently am using Twenty Thirteen and wish to move the content to the left as the indent is very large. I believe this is achieved by making the sidebar smaller.

After reading other posts I have made a child theme style.css file and added the following:

.sidebar .entry-header,
.sidebar .entry-content,
.sidebar .entry-summary,
.sidebar .entry-meta {
padding: 0 300px 0 0px;
}

However this doesn’t seem to affect the layout on the site at all. Any suggestions/ troubleshooting tips?

Also am I adding the right code for this theme?

Thanks