styles.css

html, body {
  margin: 0;
  padding: 0;
  background: #222;
  color: #eee;
  font-family: monospace;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100vh;
  overflow: hidden;
}

#score {
  margin-right: 12px;
  font-size: 25px;
}

#top {
  display: flex;
  align-items: center;
  margin-bottom: 4px;
}

#mainRow {
  display: flex;
  align-items: flex-start;
}

#gameCanvas {
  background: #111;
  margin-top: 10px;
  box-shadow: 0 0 12px #0ff, 0 0 24px rgba(0,255,255,0.3);
}

#nextCanvas {
  background: #111;
  box-shadow: 0 0 12px #0ff, 0 0 24px rgba(0,255,255,0.3);
  margin-top: 10px;
  margin-left: 20px;
}

#info {
  margin-top: 18px;
  text-align: center;
  line-height: 1.4em;
}

.key {
  background: #444;
  padding: 2px 5px;
  border-radius: 3px;
}