You can look in your css file for this –
.sidebar {
width: 30.555555555%;
}
…and change that to whatever size you want.
Depending on which page you want to edit for the content, you can change them by looking under here –
/* 04b - 1152px CSS Grid ----------- */
you can play around with the percentages like 29%, 28%, 25%, etc until you get it to the size you want….same thing for the content.
You shouldn’t have to adjust anything in your responsive section since its already setup to adjust when activated.