Hi there,

To decrease the size of the header widgets spacing on mobile you can use the following CSS code. This code can be added to Appearance -> Customize -> Additional CSS:

.header-widgets .widget {
    padding: 7px 0 5px 0;
}

To, slightly, decrease the spacing of the header logo + navigation toggle area you can also add:

.navbar-toggle {
    margin: 15px 0;
}

Hope this helps.

You're welcome