body {
  font-family: Helvetica, sans-serif;
  text-align: center;
}

hr {
  max-width: 500px;
}

#errors {
  color: coral;
}

#board {
  width: 360px;
  height: 360px;

  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
}

.tile {
  width: 36px;
  height: 36px;
  border: 1px solid lightgray;

  /* Text */
  font-size: 20px;
  font-weight: bold;
  display: flex;
  justify-content: center;
  align-items: center;
}

#digits {
  width: 360px;
  height: 40px;

  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
}

.number {
  width: 33px;
  height: 33px;
  border: 1px solid black;
  margin: 1.5px;
  text-align: center;
  /* Text */
  font-size: 15px;
  font-weight: bold;
  display: flex;
  justify-content: center;
  align-items: center;
}

.number-selected {
  background-color: gray;
}

.tile-start {
  background-color: whitesmoke;
}

.horizontal-line {
  border-bottom: 1px solid black;
}

.vertical-line {
  border-right: 1px solid black;
}

p {
  text-align: center;
  margin-top: 20px;
  font-family: Helvetica;
  font-size: 15px;
}

.gameboard {
  display: block;
  margin-left: auto;
  margin-right: auto;
}