Click to Tweets allow you to place quotes within your posts that encourage users to share those quotes directly onto Twitter with a link back to your site. In this section of the settings, you can select from several pre-configured visual styles.
While the style names are not actually descriptive of what they look like (they’re named after some of my favorite classic rock songs), the example Click to Tweet below the select box will update in real time to show you how it will look in your posts.
If you have selected Create Your Own CSS in Your Theme, you can write in your own custom-coded styles for the Click To Tweet. Here are some of the selectors you might want to use:
The top-most parent selector is:
The inner text selector is:
The button text is:
And the Twitter icon is: