Ok.

But the toggle menu on landscape always is active now ....

The media query px should be replaced in all max-width and not just the first line, like
@media only screen and (max-width: 1024px),
only screen and (-webkit-min-device-pixel-ratio: 1.5) and (max-width : 1024px),
only screen and (-o-min-device-pixel-ratio: 3/2) and (max-width : 1024px),
only screen and (min-device-pixel-ratio: 1.5) and (max-width : 1024px) { ...

same with 1026px media query.
Also in your media query in custom.css you should also change the 799px with 1024px and remove the

/* Visibility */
nav.mainNavigation ul.menu ul,
nav.mainNavigation ul.menu ul ul,
nav.mainNavigation ul.menu li:hover ul { display:block; }
since it is now covered by the other media query in template.css

Many many many thanks !!!

Now it's working perfect !

Hello another time ...

Now the problem is with sub-items, in responsive menu isn't displayed ...

Thanks.

In line 2057 (template.css) there is the following statement.
nav.mainNavigation ul.menu ul, nav.mainNavigation ul.menu ul ul, nav.mainNavigation ul.menu li:hover ul { .... }

replace the display:none; with display:block;

Great ! Now it's working perfect.

Many thanks !