index.css

body, html {
	width: 100%;
	height: 100%;
	margin: 0px;
	border: 0px;
	font-family: sans-serif;
}

.main {
	width: 500px;
	position: fixed;
	left: 50%;
	top: 50%;
	margin-left: -250px;
	margin-top: -250px;
}

.minefield {
	color: #ddd;
	font-family: sans-serif;
	font-size: 24px;
	margin: auto;
	position: relative;
	-webkit-transition: left 1s, top 1s, width 1s, height 1s;
}

.minefield-unit {
	background: #fff;
	border-radius: 5%;
	display: -webkit-box;
	-webkit-transition: box-shadow 1s, left 1s, top 1s, width 1s, height 1s, background-color 0.25s;
	/*-webkit-transition: border .5s, box-shadow .5s, background-color .5s; /* Safari and Chrome */*/
	/*box-shadow: 0px 0px 2px 2px rgba(0,0,0,0.25);*/
	-webkit-box-orient:horizontal;
	-webkit-box-pack:center;
	-webkit-box-align:center;
}

.minefield-unit.near-bomb {
	/*background: #999;*/
}

.minefield-unit.bomb:not(.covered) {
	background: #000;
	border-color: #fff;
}

.minefield-unit.covered {
	background: #eee;
	border: 1px solid #bbb;
	margin-left: -1px;
	margin-top: -1px;
}

.minefield-unit.covered.flag-certain {
	border-color: #900;
	background: #f66;
}

.minefield-unit.covered.flag-uncertain {
	border-color: #930;
	background: #f96;
}

.minefield-unit .bomb-count {
	display: block;
	margin: 0px;
	cursor: default;
}

.minefield-unit.covered .bomb-count, .minefield-unit.bomb .bomb-count, .minefield-unit:not(.near-bomb) .bomb-count {
	visibility: hidden;
}