I made this theme by using this photo. This photo is the rock garden in the Ryoanji Temple of Kyoto.
File:龍安寺 石庭.jpg - Wikimedia Commons https://commons.wikimedia.org/wiki/File:%E9%BE%8D%E5%AE%89%E5%AF%BA_%E7%9F%B3%E5%BA%AD.jpg
Ryōan-ji - Wikipedia https://en.wikipedia.org/wiki/Ryōan-ji