styles.css

/*  Base styles */
* {
  padding: 0;
  margin: 0;
  border: 0;
  line-height: 0;
  box-sizing: border-box;
}

body {
  padding-top: 1em;
  background: #B8E986;
}

h1, p {
  text-align: center;  
}

h1 {
  margin-bottom: 2em;
  margin-top: 1em;
  line-height: 0;
  color: #324654;
}

a {
  text-decoration: none;
  color: #F6A623;
}

.reference {
  margin-top: 1em;
  color: #324654;
}

#dashboard {
  color: #F6A623;
}
/* Board styles */

.board {
  margin: 1em auto;
  width: 600px;
  height: 600px;
  border: 3px solid #324654;
}

.board div {
  display: inline-block;
  width: 198px;
  height: 198px;
  border: 1px solid #324654;
  float: left;
}

.board .blank {
  cursor: pointer;
}

.board .x,
.board .o {
  font-size: 80px;
  line-height: 80px;
  text-align: center;
  vertical-align: middle;
  float: left;
  padding: 50px 0 0 0;
  background-size: 160px 160px;
  background-position: center center;
  background-repeat: no-repeat;
}

.board .x {
  background-image: url("images/x.png");
}

.board .o {
  background-image: url("images/o.png");
}

.game-over {
  color: #324654;
  font-size: 2em;
  display: block;
  padding-top: 200px;
  margin-bottom: 1em;
}

.reload {
  display: block;
  font-size: 1.2em;
  text-align: center;
  color: #6EA223;
}