Hello
To amend try adding the following to the Custom CSS field of your templates parameters (Extensions -> Templates -> [YourTemplateStyle] -> Custom CSS)....
@media only screen and (max-width: 768px) {
.logo-text h1, .logo-text h1 a {
white-space: normal;
text-align: center;
font-size: 25px;
}
}
Edit to taste
Ciaran