body {
  text-align: center;
  user-select: none;
  -moz-user-select: none;
  -webkit-user-drag: none;
  -webkit-user-select: none;
  -ms-user-select: none;
}

hr {
  width: 500px;
}

#errors {
  color: coral;
}

#board {
  width: 450px;
  height: 450px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
}

#digits {
  width: 450px;
  height: 50px;

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

.tile {
  width: 48px;
  height: 48px;
  border: 1px solid lightgray;

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

.number {
  width: 44px;
  height: 44px;
  border: 1px solid black;
  margin: 2px;

  font-size: 20px;
  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: 2px solid black;
}

.vertical_line {
  border-right: 2px solid black;
}