:nth-child() test

1. Hydrogen
2. Helium
3. Lithium
4. Beryllium
5. Boron
6. Carbon
7. Nitrogen
8. Oxygen
9. Fluorine
10. Neon

li:nth-child( )

The pattern is An+B (documentation). Examples:

• 5
• 2n + 1
• -n + 3
• odd
• even