Generate a poster explaining the usage cycle of replacing the brush head of an electric toothbrush, without the need for the complete product body. The upper half of the image has a blank white background, with a black modern sans-serif title in the upper left labeled "Color Reminder / Timely Replacement." The two lines of dark gray below indicate "The bristle color will gradually lighten with daily use, making it easier to judge when to replace." Below the title, there are two small dotted labels: the left side is bright blue for "Early Use," and the right side is light gray for "Recommended Replacement."
The lower half is a close-up of an enlarged round brush head, with the background divided by a vertical dashed line in the center: light blue-white on the left and light gray-blue on the right. The left bristle ends have a clear blue gradient, while the right bristles are pale white and blue; The bristles are fine, neatly arranged, and have a realistic texture. The layout is simple and gives plenty of breathing room, with titles aligned to the left and descriptions and a style close to rational sans-serif lines. Do not include original brands, original numerical scales, size parameters, footnotes, watermarks, or screenshot borders.
