How the thread is built
One comment per line, in order, with blank lines ignored. A leading greater-than sign marks the comment as yours, which switches the avatar colour and the handle. Instagram runs the handle inline with the first words of the comment, so that is how this renders, with the like count on the line underneath.
The image is drawn on an HTML canvas rather than screenshotted from the page. Text is measured and wrapped to the available column, the avatar circle is drawn per comment, and the canvas grows to fit the thread. It renders at twice the display resolution.