Centre Center nav menu items with themselves

Main Menu - Nav Items

/*Centre nav items under themselves*/
.tm-header .uk-navbar-nav > li > a {
text-align: center;
}

Should you want align the text at the top, use this ruleset instead:

.tm-header .uk-navbar-nav > li > a {
display: flex;
align-items: flex-start;
text-align: center;
}

For the footer

.uk-nav-sub {
flex-direction: column;
align-items: center;
}

For the header