Project: selector
Task (challenging): write css for elements in `#form`:
- set `background-color` to `yellow` for those without attribute `name`
- set `background-color` to `red` for those whose attribute `name` starts with `form`
- set `background-color` to `green` for those whose attribute `name` ends with `end`
- set `background-color` to `blue` for those whose attribute `class` contains `c2`
- set `background-color` to `white` for those whose attribute `name` equals to `form-1`
- set `background-color` to `white` for those whose attribute `name` contains `unique`
- set `background-color` to `white` for those whose attribute `lang` starts with `en` immediately followed by a hyphen