CSS not working

Hi. I’m trying to use in “Ivory Search – Settings – Custom CSS”

@media only screen and (min-width:1001px){
<!– For desktop –>
.main-navigation li.is-menu {
float: right;
}
}

@media only screen and (max-width:1000px){
<!– For mobile –>
<!– (coming soon) –>
}

but is not working, while using

.main-navigation li.is-menu {
float: right;
}

works fine.

I can’t see the problem. Can you help me, please?
Thanks in advance.
Regards,
B.

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