Flat composition, also known as composition in two dimensions, is a fundamental concept in graphic design and visual arts. It involves arranging visual elements such as shapes, lines, colors, and textures in a harmonious and structured manner to create a balanced and aesthetically pleasing composition. The term 'skeletal gradient' suggests a design that utilizes a gradient to emphasize the structure or framework of the composition, creating a sense of depth and focus. This type of poster combines principles of flat design with visual effects to convey a message or theme effectively.