1. A display control device that controls a display unit having a screen to perform displaying, the display control device comprising: a management unit configured to manage items each belonging to any one of categories; a screen attention degree determination unit configured to determine a screen attention degree indicating how much a user pays attention to the screen of the display unit; a selection operation history collection unit configured to collect selection operation history information indicating a history of selection of each of the categories; a selection probability calculation unit configured to calculate a selection probability of being selected by the user, for each of the categories based on the screen attention degree and the selection operation history information; and a display style determination unit configured to (i) determine a display style allowing the user to more easily select an item in a category having a higher selection probability among the categories, and (ii) cause the display unit to display the item in the determined display style, wherein the categories include a relevance category that is a category including items related to a piece of content displayed on the screen, and the selection probability calculation unit is configured to: calculate a selection probability of the relevance category in a case where the screen attention degree is a first attention degree to be higher than a selection probability of the relevance category in a case where the screen attention degree is a second attention degree that is lower than the first attention degree; and calculate, for each of the categories, a selection probability in a case where a total number of selection times the each of the categories has been selected is a first number, to be higher than a selection probability in a case where the total number of the selection times is a second number that is smaller than the first number, the calculating being performed based on the selection operation history information.