style.css

body {
  margin: 0;
  padding: 0;
  font: 14px "Helvetica", Arial, sans-serif;
}

button {
    text-align: center;
    font-size: 4em;
    padding: 0.2em 1em;
    border-radius: 0.5em;
    background: #c6e8ff;
    border: 1px solid #a7c6e5;
    box-shadow: 1px 1px 5px rgba(0,0,0,0.2);
}

.gameContainer {
  padding-left: 0;
  padding-right: 0;
}

.container {
  max-width: 45em;
  margin: 2em auto;
  padding-left: 1em;
  padding-right: 1em;
}

header {
  background: #f4fbff;
  border: 1px solid #d9edf4;
  box-shadow: 1px 1px 5px rgba(0,0,0,0.2);
}

h1 {
  margin-bottom: 0.5em;
}


.midiStatus {
  margin-top: 2em;
  text-align: center;
  font-size: 2em;
  line-height: 1.6;
}

.bigEmoji {
  font-size: 4em;
}

.startScreen {
  text-align: center;
  margin-top: 4em;
}

.center {
  width: 100%;
  height: auto;
}

.treble {
  font-size: 280px;
}

.testControls {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: #f4fbff;
  border: 1px solid #d9edf4;
  box-shadow: 1px 1px 5px rgba(0,0,0,0.2);
  padding: 2em 1em;
  text-align: center;
}

.testControls h1 {
  margin: 0.5em 0 0.5em;
  font-size: 1.2em;
  font-weight: normal;
}

.testControls button {
    text-align: center;
    font-size: 1.5em;
    padding: 0.2em 1em;
    margin: 0.1em;
    border-radius: 0.5em;
    background: #c6e8ff;
    border: 1px solid #a7c6e5;
    box-shadow: 1px 1px 5px rgba(0,0,0,0.2);
}

.sprite {
  image-rendering: pixelated;
  image-rendering: -moz-crisp-edges;
  image-rendering: crisp-edges;
  /*
  see
  https://css-tricks.com/almanac/properties/i/image-rendering/
  */
}