Cannot have the content of the center column before the sidebar

I don’t know why but part of the homepage content in th central column always appears under the sidebar. Actually, it’s the posts extracts.
I have first some customised content which appears correctly at the top of the column but there is a big blank area between this content and my posts extracts.

The layout is fine for page or post content.

The website is here : https://femmesprit.site40.net/

And here is my index.php:

[code moderated according to Forum Rules - please use the pastebin]

Thanks for your help.