body {
  font-family: "Helvetica Neue";
  background-color: #87cefa;
  color: black;
}

h1 {
  margin: 16px auto;
  text-align: center;
  font-size: 4em;
}

h2 {
  margin: 16px auto;
  text-align: center;
  font-size: 1.5em;
}

#checkbox{
  margin-left:685px;
}

.whose_turn {
  margin: 10px auto;
  margin-bottom: 20px;
  text-align: center;
  font-size: 1.5em;
}

/* Button: NewGame and Reset */
.new_game, .reset {
  text-align:center;
  background-color: #ff8c00;
  color: #000000;
  font-size: 24px;
  padding: 12px 28px;
  border-radius: 12px;
  border: 1px solid gray;
  display: block;
  margin: 20px auto;
}

.new_game:hover, .reset:hover {
  background-color: orange;
}

.game_board {
  width: 500px;
  height: 500px;
  border: 4px solid black;
  display: flex;
  margin: 0 auto;
}

.row {
  display: flex;
  flex-wrap: wrap;
}

.one, .two, .three, .four, .five, .six, .seven, .eight, .nine {
  flex-grow: 1;
  width: 100px;
  background-color: pink;
  border: 4px solid black;
  box-sizing: border-box;
  position: relative;
}

.xo {
  color: black;
  font-weight: bold;
  font-size: 8em;
  margin: 0 auto;
  position: absolute;
  width: 100%;
  text-align: center;
}