Start from the supplied illustrated first frame. Locked front view. Keep the side support and its visible pivot fixed. Rotate the sealed rectangular vessel only a small amount clockwise around that pivot. Keep the original cap attached and both liquid and air inside the original unbroken walls. Let the internal liquid surface respond with a modest slosh and settle toward a level orientation instead of rotating rigidly as a painted stripe on the vessel. Preserve a visible air pocket. Do not pour, leak, add liquid, introduce a new opening or move the camera. Stop at the small tilted pose and hold while the surface settles qualitatively. No exact volume, wave timing or optical-refraction target.