How to change site title font

Change of these parameters is not provided via options in Basict heme. This can be done only by means of CSS styles.

In field Custom styles in menu Appearance → Customize → Custom codes enter the following CSS code, replacing 24px with font size that you need (changing this number in field with CSS code, you will immediately see changes in preview window):

#logo { 
   font-family: 'PT Serif', Tahoma, Verdana, Segoe, sans-serif; /* family */
   font-size: 60px;   /* font size in pixels */
   line-height: 125%; /* line height in percents */
   color: #993366;    /* text color */
}

For site tagline use code below:

.sitedescription { 
   font-family: Arial, "Helvetica Neue", Helvetica, sans-serif; /* семейство шрифта */
   font-size: 16px;   /* font size in pixels */
   line-height: 140%; /* line height in percents */
   color: #222222;    /* text color */
}

Value for font family you can get fron web-safe fonts list. Hex color code find here.