1. A computer implemented method for masking objects using predefined colors, the method comprising: identifying a first predefined color and a second predefined color, the first and second predefined colors being included in a Cascading Style Sheets (CSS) style sheet used by a webpage; receiving an object to be added to the webpage, the object having an object color; calculating, by a processor, a first color similarity score for the first predefined color and a second color similarity score for the second predefined color, the color similarity scores indicating a level of similarity between the predefined colors and the object color; comparing the first color similarity score to the second color similarity score; determining, based on the comparing, a mask color, the mask color being the predefined color that is most similar to the object color; and masking the object using the mask color.