.sudoku {
min-height: 2.6em;
width: 2.6em;
border-radius: 4px;
overflow: hidden;
box-shadow: 0 2px 1px rgba(0,0,0,0.07),0 1px 3px 1px rgba(0,0,0,0.14);
transition: all 0.13s ease-in-out;
}
.sudoku:hover {
z-index: 3;
box-shadow: 0 10px 9px rgba(0,0,0,0.07), 0 12px 75px 12px rgba(0,0,0,0.14);
transform: scale(1.01);
}
.sudoku:active {
z-index: 1;
box-shadow: 0 10px 10px rgba(0,0,0,0.14), 0 0 20px 0 rgba(0,0,0,0.28);
transform: none;
transition: all 0.04s ease-in;
}