Original CSS on a theme is not working after to change somthings

Hi there,

I’m working on an Agency theme from the site library. The CSS that comes originally in the theme for a button in the main menu (Contact button) doesn’t work. The CSS is wrote there like it’s come, but doesn’t do nothing…
I have deactivated plugins and cleared caches several times, but nothing works.

The CSS is this :

/* GeneratePress Site CSS */ /* navigation contact button */

.main-navigation:not(.slideout-navigation) .main-nav li.nav-button a{
color: #ffffff;
background-color: #789602;
line-height: 44px; /* button height */
padding: 0px 22px; /* space inside button */
margin-top: 4px; /* adjust to horizontally align with other menu items */
border-radius: 40px;
margin-left: 22px; /* space to the left of button */
transition: all 0.4s ease 0s;
}

.main-navigation:not(.slideout-navigation) .main-nav li.nav-button a:hover{
background-color: rgba(174, 194, 0, 0.85);
color: #ffffff;
transition: all 0.4s ease 0s;
}

/* mobile header spacing */

.mobile-header-navigation {
padding: 10px;
}

/* lightweight social icon styling */

.lsi-social-icons li a, .lsi-social-icons li a:hover {
padding: 0px !important;
margin: 0px 4px 0px 0px !important;
background: transparent !important;
} /* End GeneratePress Site CSS */

Can someone help me? I don't know what to do...

Thanks!
Jaime