Too much space at the top and bottom (StoreFront)

Please open your css file below link:
https://www.atelier-caberu.fr/wp-content/themes/storefront/style.css?ver=2.7.0

change line number: 714 following code

.page-template-template-homepage:not(.has-post-thumbnail) .site-main {
padding-top: 0.005801032em;
}

or see the screen shot.

https://ibb.co/ByWpcgY

Thanks

Don’t edit the theme’s CSS. Use the Customizer.

To add or override CSS: use the “Additional CSS” option in the customizer. https://www.ads-software.com/support/article/appearance-customize-screen/