Custom theme not affecting panel

I am trying to play with custom themes, but the first thing that I walk into is an example from the docs that is not working. Anyone got any ideas?

.fi-topbar {
    @apply bg-gradient-to-l from-[#009CC3] to-[#02B1DE];
}

.fi-topbar {
    @apply bg-gradient-to-l from-[#009CC3] to-[#02B1DE];
}

.fi-topbar {
    @apply bg-gradient-to-l from-[#009CC3] to-[#02B1DE];
}

.fi-topbar {
    @apply bg-gradient-to-l from-[#009CC3] to-[#02B1DE];
}

I followed every step on https://filamentphp.com/docs/3.x/support/style-customization. As seen in the picture, the background is affected, but it does not seem to work properly like the docs is showing.