html, body {
  height: 100%;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  -webkit-user-select: none; /* Chrome, Safari, and Opera */
  -moz-user-select: none;    /* Firefox */
  -ms-user-select: none;     /* Internet Explorer/Edge */
  user-select: none;         /* Standard syntax */
}

.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  width: 100%;
  flex-direction: column;
}

button {
 -webkit-tap-highlight-color: transparent;
  width: 100%;
  font-size: 30px;
  background-color: white;
  color: black;
  cursor: pointer;
}

button:active {
  background-color: black;
  color: white;
}