Logo in header in centre when viewing on mobile

For an upload logo, use Center Header Logo and for site title text use Center Site Title.

// Center Header Logo //

@media only screen and (max-width: 640px) { .header-title-logo {
    width: 120%;
    text-align: center;
}
}

// Center Site Title //

@media only screen and (max-width: 640px) { .header-title-text {
    width: 120% !important;
    text-align: center !important;
}
}