Hey Theweblady,
The logo size depends on the image you upload in the Theme Options panel – please try uploading a smaller version of the image.
Regarding the tagline font size – it is not settable via the back-end, yet you can easily change it by using some custom CSS: just insert this code at the very end of the theme’s “style.css” file (opens by default when you visit “Appearance -> Editor” admin menu:
#slogan { font-size: 14px !important; line-height: 20px !important; }
You can change the px values to any ones you need ;)
Sincerely,
Andrii / Satori Studio