Here's another small experiment with CSS3, this time applying some logic to the application, which in this case is a Sudoku game. It is a Sudoku solution checker which is purely performed with CSS. It uses attribute selectors and the general sibling combinator (~), as such browsers that do not support those selectors, will not function correctly. The CSS checks that each value is unique in the row, in the column, and within each of 9 individual 3x3 tables. If a duplicate is found within one of those, a number which conflicts is colored red.