style.css

* {
  font-family: Helvetica;
  color: #34495e;
}

.container {
  background-image:url('background.png');
  width: 100%;
  height: 100%;
}

h1 {
  font-size: 2.3em;
  text-align: center;
  margin: 0px 0px 10px 0px;
}

table {
  margin: 0 auto;
  border-spacing: 5px;
}

td {
  width: 100px;
  height: 100px;
  background-color: #95A5A6;
  border-radius: 5px;
  color: #FFF;
  text-align: center;
  font-size: 5em;
  transition: 0.25s;
}

td:hover {
  background-color: #BDC3C7;
  transition: 0.25s;
}

.reset-button {
  position: relative;
  font-size: 1.2em;
  color: #FFF;
  padding: 10px;
  background-color: #2980B9;
  transition: 0.25s;
  border-radius: 5px;
  margin: 0 auto;
  margin-top: 10px;
  left: 78px;
  width: 140px;
  text-align: center;
}

.reset-button:hover {
  background-color: #3498DB;
}

td.X {
  background-color: #C0392B;
}

td.O {
  background-color: #34495E;
}

.winner {
  width: 316px;
  color: #FFF;
  background-color: #D35400;
  margin: 0 auto;
  margin-top: 10px;
  border-radius: 5px;
  font-size: 2em;
  text-align: center;
  padding: 10px 0px;
}