webapp/src/index.css
body {
  background: #353433;
  color: #e9e8e7;
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  font-size: 20px;
  text-align: center;
  overflow-x: hidden;
}

.loading {
  color: #8b8685;
}

.loading p {
  margin: 30px 0;
}

.Flipper {
  margin: 20px auto 0;
  position: relative;
  background: #090807;
  width: 100vw;
  height: 100vw;
  max-width: 440px;
  max-height: 440px;
  perspective: 880px;
  user-select: none;
}
.Flipperのrotor,
.Flipperのfront,
.Flipperのback {
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
}
.Flipperのrotor {
  transform-style: preserve-3d;
}
.Flipper.is-flipped .Flipperのfront {
  pointer-events: none;
}
.Flipper:not(.is-flipped) .Flipperのback {
  pointer-events: none;
}
.Flipperのfront {
  transform: rotateY(0deg);
}
.Flipperのback {
  transform: rotateY(180deg);
}
.Flipperのfront,
.Flipperのback {
  backface-visibility: hidden;
  transform-style: flat;
}

.err {
  position: absolute;
  appearance: none;
  cursor: pointer;
  background: #8b8685;
  top: 0; right: 0; bottom: 0; left: 0; width: 100%; margin: 0;
  text-align: center;
  box-sizing: border-box;
  border: 0;
  font: inherit;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #e9e8e7;
  text-shadow: 0 -1px 0 rgba(0,0,0,0.5);
  animation: 1.2s please-input-id linear;
}
.err-text {
  display: block;
  flex: 1;
  text-align: center;
}

@keyframes please-input-id {
  0% { transform: scale(1); }
  40% { transform: scale(1); animation-timing-function: ease; }
  50% { transform: scale(1.1); animation-timing-function: ease; }
  60% { transform: scale(1); }
  80% { transform: scale(1); animation-timing-function: ease; }
  90% { transform: scale(1.1); animation-timing-function: ease; }
  100% { transform: scale(1); }
}

.qrcode-container {
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  cursor: pointer;
}

.qrcode {
  animation: 0.5s here-be-qr linear;
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
}

.qrcode svg,
.qrcode img,
.qrcode canvas {
  position: absolute;
  top: 0; left: 0; width: 100%; height: 100%;
}
.qrcode canvas {
  background: white;
  object-fit: contain;
  image-rendering: pixelated;
}

.qr-explanation {
  margin: 5px auto 20px;
  color: #8b8685;
  font-size: 12px;
}

@keyframes here-be-qr {
  0% { transform: rotate(-480deg) scale(0); }
  80% { transform: rotate(0deg) scale(1.05); }
  100% { transform: rotate(0deg) scale(1); }
}

.amount {
  font-size: 36px;
  color: #8b8685;
}

.amount input {
  font: inherit;
  width: 4em;
  background: #090807;
  border: 1px solid #454443;
  color: #d7fc70;
  text-align: right;
}

.tip {
  font-size: 12px;
  margin: 20px 0;
  color: #8b8685;
}

.tip a {
  color: #9b9695;
  text-decoration: none;
}

h1 {
  margin: 20px 0;
  font-size: 32px;
  color: #8b8685;
}

.SlotSelector {
  position: absolute;
  top: 0; right: 0; bottom: 0; left: 0;
  background: #454443;
  display: flex;
  flex-direction: column;
  border: 1px solid #555453;
}
.SlotSelectorのitem {
  height: 25%;
  flex: 1;
  box-sizing: border-box;
  background: #252423;
  border: 0;
  font: inherit;
  color: inherit;
  appearance: none;
  display: flex;
  align-items: center;
  transition: 0.1s transform;
  margin: 0;
}
.SlotSelectorのitem:not(:first-child) {
  margin-top: 1px;
}
.SlotSelectorのitem:focus {
  outline: none;
}
.SlotSelectorのitem.is-active {
  background: #8b8685;
}
.SlotSelectorのitem:active {
  transform: scale(0.95);
}
.SlotSelectorのnum {
  display: block;
  margin: 0 20px;
  width: 1.5em;
  height: 1.5em;
  line-height: 1.5em;
  text-align: center;
  background: #454443;
  font-weight: bold;
  border-radius: 5px;
}
.SlotSelectorのitem.is-active .SlotSelectorのnum {
  background: #e9e8e7;
  color: #353433;
}
.SlotSelectorのinfo {
  display: block;
  flex: 1;
  text-align: left;
}
