is a format developed by the International Digital Publishing Forum. It is characterized by the XML- and XHTM-based optional use of CSS styling. The main feature of this format is the use of reflowable text (word wrap) which makes it possible to adapt the image to different device displays. The ePub file is a zip-archive with an .epub extension.
Format for representing colors in the three primary colors (red, green and blue), each of which has 255 gradations. In contrast to the standard RGB, it allows you to change the transparency of the entire image using the opacity parameter. It is less flexible in terms of transparency settings than RGBA.