If you search for this in your css (around line 888) –
.sidebar-secondary {
float: left;
width: 180px;
}
That is how you can adjust the left sidebar.
To adjust the main content area look for this in your css (around line 864) –
.content-sidebar-sidebar .content,
.sidebar-content-sidebar .content,
.sidebar-sidebar-content .content {
width: 520px;
}