蓝色立体卡通信封里装着白纸元素

A 3D blue envelope cartoon-style design with an open flap, the paper slightly exposes rounded and cute corners, a pure white background with no shadows, soft ambient lighting, overall fresh and clean, elements occupy 55% of the screen, with uniform white space around, 1:1 square, 3D C4D rendering, rounded and flat office style.