You can easily change the color, font family, font size of your blog. To make blogger description font small, you need to perform the following steps:
1. Log in to Blogger and go to the dashboard of your blog.
2. From the left hand menu select "Template"
3. On the Templates Page select "Edit HTML" under Live Blog.
4. From the top menu select "Jump to Widget" and then "Header 1" from the drop down menu.
5. Find this line:
< b:widget id='Header1' locked='true' title='Your Blog Name (Header)' type='Header'>...< /b:widget>
6. Now click on the dots that appear between type='Header'> and < /b:widget> to expand the section.
7. You should now see the following code
< b:section class='header' id='header' maxwidgets='1' showaddelement='no'> < b:widget id='Header1' locked='true' title='Your Blog Name (Header)' type='Header'>
< b:includable id='main'>
< b:includable id='description'>...< b:includable>
< b:includable id='title'>
< /b:includable>
< /b:widget>
< /b:section>
8. Click on the dots between < b:includable id='description'> and < /b:includable>
9. Now you will presented with this code:
< b:includable id='description'>
< div class='descriptionwrapper'>
< p class='description'>
< data:description/>< /p> < /div>
10. Find this line:
< p class='description'>< span>
< /span>< /p>
11. Now to change the blog description to a different font eg default to verdana change the code to the following
< p class='description' style='font-family: verdana;'>< span>
< /span>< /p>
12. To change the blog description font style to italics change the code to the following
< p class='description' style='font-family: verdana; font-style: italic;'>< span>
< /span>< /p>
13. To change the font style of your blog description from the default capitalized case to uppercase change the code as follows. Note for lower case use: text-transform: lowercase;
14. To increase the size of the blog description font from 12px to 16px for example change the code to the following
< p class='description' style='font-family: verdana; font-size: 16px;'>< span>
< /span>< /p>
15. Putting all the changes together from 11 to 14 would need the following code change
< p class='description' style='font-family: verdana; font-style: italic; text-transform: uppercase; font-size: 16px;'>< span>
< /span> < / p>
This is how you can change the font size, text, font style, font-family of your blog through code. Or you can simply follow above answer as described by @aryan for easier process.