Adding menu’s to your WordPress theme > https://since1979.dev/snippet-003-adding-menus-to-your-theme/

snippet-003-basic-menu-styling.css

/**
* Add some basic styling to "header-menu".
*
* @see https://since1979.dev/snippet-003-adding-menus-to-your-theme/
*/
.menu-header-menu-container {
    display: block;
    /* Align menu left or right */
    text-align: right;
}
.menu-header-menu-container ul {
    display: inline-block;
    margin: 0;
    padding: 0;
    list-style: none;
}
.menu-header-menu-container li {
    display: inline-block;
    /* Change margins if menu is left aligned */
    margin: 0 0 0 10px;
    padding: 0;
    list-style: none;
}
.menu-header-menu-container li a {
     color: #666666;
     text-decoration: none;
}
/* Set hover/active states */
.menu-header-menu-container li a:hover,
.menu-header-menu-container li.current_page_item a,
.menu-header-menu-container li.current-page-ancestor a {
    color: #000000;
}