My recommendation is to use a modern, ideally full-site editing, theme.

But if you choose to build your new site with such an old theme, you need to either settle for its limitations… or be willing to write custom code to achieve any modern enhancements you desire.

You may try the following custom CSS to reduce/remove the margins (put in APPEARANCE > CUSTOMIZE > ADDITIONAL CSS):

#page {
    max-width: unset;
}

This will drastically reduce the margins on either side of the page. If you want to remove all the margins, add this as well:

body {
    padding: 0;
}

With more horizontal space at your disposal now, you may want to increase the width of the content area and/or right sidebar. Let me know if this is of interest to you as well.

Good luck!

Lot of thanks for your advice.

On another thread, I have been looking for a latest theme with header images rotation. I was suggested using “Theme Twenty Seventeen”. But it is also an old theme which I have used in the past. What will be your recommendation? Thanks in advance.

Regards

Again

I have used “Theme Twenty Eleven” building WP websites for long time. They are still running on Internet without problem. The page width of website can be adjusted without problem. Unfortunately I forgot the steps.

tours-video.com is an example running Theme Twenty Eleven. I have >40 WP sites still running on Internet. Most of them use Theme Twenty Eleven.

I’ll search my DATABASE to see whether I can the steps

Regards

I have used “Theme Twenty Eleven” building WP websites for long time. They are still running on Internet without problem. The page width of website can be adjusted without problem. Unfortunately I forgot the steps.

I installed the theme and went over its settings before responding to your post.

The Twenty Eleven theme itself simply does not have this feature — unless you’re using a modified version of the theme or the feature is provided by a helper plugin.

Of course, you may search your database ??

tours-video.com is an example running Theme Twenty Eleven. I have >40 WP sites still running on Internet. Most of them use Theme Twenty Eleven.

tours-video.com is using a Twenty Eleven child theme. So it’s possible the feature — if you have it on this site — may have been baked into the child theme… but it’s certainly not from the original parent theme.