---

first-child选择列表中的第一个标签

li:first-child {color: red;
}

---

last-child选择列表中的最后一个标签

li:last-child {color: pink;
}

---

nth-child(n)选择列表中的第n个标签

li:nth-child(3) {color: pink;
}

---

nth-child(2n)选择列表中的偶数位标签

li:nth-child(2n) {color: pink;
}

---

nth-child(2n-1)选择列表中的奇数位标签

li:nth-child(2n-1) {color: pink;
}

---

nth-child(n+m)选择从第m个到最后一个标签

li:nth-child(n+5) {color: pink;
}

---

nth-child(-n+m)选择从第1个到第m个

li:nth-child(-n+5) {color: pink;
}

---

nth-last-child(3)选择最后3个标签

li:nth-last-child(3) {color: pink;
}

---

nth-last-child(3n)选择3倍数位的标签

li:nth-last-child(3n) {color: pink;
}

---

nth-last-child(3n-1)选择等差数列的标签

li:nth-last-child(3n-1) {color: pink;
}