/* ------------ ่ฆชๅญ้ไฟ ------------ */
/* ไธไธๅฎๆฏ็ดๆฅ็่ฆชๅญ้ไฟ */
ancestor descendant /* op: space */
/* ็ดๆฅๅญๅ
็ด */
parent > direct-child
/* ็ดๆฅๅญๅ
็ด ๏ผไฝไธๆฏ็ฌฌไธๅ(ไปฅไธๅฏซๆณๆๆ้ฝไธๆจฃ) */
parent > direct-child + next-siblling /* immediate sibling */