* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: sans-serif;
  background: #f4f4f4;
  color: #111;
  display: grid;
  place-items: center;
}

.app {
  width: min(92vw, 460px);
  text-align: center;
}

h1 {
  margin: 0 0 10px;
  font-size: 28px;
}

.hud {
  display: flex;
  justify-content: space-between;
  margin-bottom: 10px;
  font-size: 15px;
}

#board {
  width: 100%;
  max-width: 400px;
  border: 2px solid #222;
  background: #fff;
}

.controls {
  margin-top: 12px;
  display: grid;
  gap: 8px;
  justify-items: center;
}

.controls-row {
  display: flex;
  gap: 8px;
}

button {
  min-width: 70px;
  min-height: 36px;
  border: 1px solid #333;
  background: #fff;
  color: #111;
  cursor: pointer;
}

#restartBtn {
  margin-top: 10px;
}

.hint {
  font-size: 13px;
  color: #444;
}

@media (min-width: 760px) {
  .controls {
    max-width: 240px;
    margin-left: auto;
    margin-right: auto;
  }
}