element
  Specifies how non-data components of the plot are drawn. This theme element draws text.
Examples
Parameters
Text color. Accepts color code as a string (HEX or rgb) or Color object.
Font family.
Font face ("plain", "italic", "bold", "bold_italic").
Text size in px.
Angle to rotate the text (in degrees).
Horizontal justification (in [0, 1]).
- 0 - left-justified 
- 1 - right-justified 
- 0.5 - center-justified Values outside this range are allowed, but the behavior is unspecified. 
Vertical justification (in [0, 1]).
- 0 - bottom-justified 
- 1 - top-justified 
- 0.5 - middle-justified Values outside this range are allowed, but the behavior is unspecified. 
Margins around the text. The margin may be specified using a number or a list of numbers:
- a single number or a list of one number - the same margin is applied to all four sides; 
- a list of two numbers - the first margin applies to the top and bottom, the second - to the left and right; 
- a list of three numbers - the first margin applies to the top, the second - to the right and left, the third - to the bottom; 
- a list of four numbers - the margins are applied to the top, right, bottom and left in that order. It is acceptable to use - nullfor any side; in this case, the default side value for this element will be used.
Mark as a 'blank' element.