.float { float: left; }
div.sudoku { padding: 0 5px; }
.sudoku table { border: 1px solid red; margin: 1ex auto; line-height: 1; font-size: small; vertical-align: top; }
.sudoku tr td { border: 1px solid grey; width: 2.5em; height: 2.5em; line-height: 1; text-align: center; vertical-align: middle; font-weight: bold; font-family: sans-serif; padding: 0; margin: 0; }
.sudoku tr td.ullr { background: #0ff; }
.sudoku tr td.urll { background: #ff0; }
	.hidevalue { color: transparent; }
.sudoku del { color: #aaa; }
div.fourboards { height: 13em; width: 50em; border: 5px ridge yellow; background: #FF9; line-height: 1; }
div.fourboards::after { clear: both; }
div.fourboards h4 { margin: 0; line-height: 1; }