Hi there,
OK so a few steps:
1. Add this CSS:
@media(max-width: 768px) {
/* Minimum logo width and reduce space between logo and title */
.site-header .site-branding-container .site-logo {
min-width: 120px;
margin-right: 10px;
}
/* Reduce tag line font size */
.site-header .site-description {
font-size: 12px;
}
}
2. In Customizer > Layout > Header , select the Mobile tab and reduce the padding to 10px. I would probably leave 20px on the right, as your logo image has white space around it, and this will compensate for that.
3. If you want reduce the Mobile font size of the Customizer > Typography > Header >>> Site Title.