Adding a to Site Title

So what I want to accomplish is to make the first part of the Site Title larger font-size then the second half. i.e 3em for “Wordpess Site” and 2em for “by Robert Langley”. For the Site Description I want to break up a quote so its on two lines…..BUT I want to adjust the left margin just for the second line of the quote. Is any of this possible? I am not familiar with PHP so if it is a PHP solution(I imagine it is) I will need really simple “For Dummies” solutions. When I have added “span” tags to these two items in the theme customize section the “span” tags show up as text in the title and description. I know how to add a span with a class and customize it but WordPress will not allow me to add a “span” tag to the Site Title or Site Description. Rather then rendering it as html it displays the text. i.e “<span class=”class”>Site Title</span>By Robert”<———displays like this on the live website, as opposed to rendering it as HTML.

Adding a <span> to Site Title and Site Description