Summer poster suitable for a purple-blue gradient background

Quick answer：

A purple-blue gradient background is a visually appealing choice for summer posters as it evokes a sense of calmness and relaxation, often associated with the color blue, while the purple adds a touch of sophistication and depth. This color scheme can be used to create a serene and inviting atmosphere, suitable for various summer-themed designs such as travel, relaxation, or outdoor activities.