Answer:
Colour, Fonts, Effects
Step-by-step explanation:
A Theme can be defined as a unique package which often contain details in which the appearance are graphical.
A theme are made up of of a set of shapes and colors which are use for graphical control elements as well as the window decoration and the window which is why Themes are often used to customize the look and feel of a computer software because they tend to relies heavily on graphic elements.
Therefore the components that are main part of themes are COLOR, FONTS AND EFFECTS