Simple Tile Game

<!DOCTYPE html>
<html>
    <head>
        <style>
            .block {
                fill: white;
                stroke-width: 4px;
                stroke: lightgray;
            }
            .block.selected, .block.selected .symbol path {
                fill: none;
                stroke: none;
            }
            .moving-block {
                display: none;
            }
            .moving-block.selected {
                display: inherit;
                fill: #e0e0e0;
                stroke-width: 4px;
                stroke: gray;
            }
            .selectable {
                stroke: grey;
                fill: #f6f6f6;
            }
            .path {
                fill: #c9c9c9;
                stroke: grey;
            }
            .path .symbol path {
                fill: grey;
            }
            .endpoint {
                fill: #a9a9a9;
                stroke: #797979;
            }
            .symbol path {
                fill: lightgrey;
                stroke-width: 0;
            }
            .selectable .symbol path, .moving-block.selected .symbol path {
                fill: gray;
            }
            .not-selected:not(.selected):not(.path) {
                fill: white;
                stroke: lightgray;
            }
            .not-selected:not(.selected):not(.path) .symbol path {
                fill: lightgray;
            }
            .player {
                fill: #f6f6f6;
                stroke: grey;
                stroke-opacity: 0.5;
                stroke-width: 4px;
            }
            .player.active-player {
                stroke-opacity: 1;
            }
            .player text, .player .symbol path {
                stroke: none;
                stroke-width: 0;
                fill: grey;
                fill-opacity: 0.5;
            }
            text {
                font-family: Arial,serif;
                font-size: xx-large;
                stroke-width: 0;
                stroke: none;
                fill: grey;
                cursor: default;
            }
            .player.active-player text, .player.active-player .symbol path {
                fill-opacity: 1;
            }
            .winning-line, .winning-player {
                fill: orange;
                fill-opacity: 0.5;
                stroke: darkorange;
                stroke-opacity: 0.5;
            }
            .winning-line .symbol path, .player.winning-player .symbol path, .player.winning-player text {
                fill: darkorange;
            }
            .menu {
                fill: white;
                stroke: grey;
                stroke-width: 4px;
            }
            .button {
                fill: lightgrey;
                stroke: grey;
                stroke-width: 3px;
                text-anchor: middle;
            }
            .button:active {
                fill: grey;
            }
            path {
                stroke: none;
                stroke-width: 0;
                fill: none;
            }
        </style>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.9/d3.min.js" charset="utf-8"></script>
        <script src="pathseg.js"></script>
    </head>
    <body>
        <div id="board"></div>
        <script src="game.js"></script>

</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.9/d3.min.js