body { font-family: Arial; }

ul li {
  list-style-position: inside;
  text-align: left;
}

.labels {
  position: fixed;
  top: 10px;
  width: 100%;
  display: flex;
  justify-content: space-between;
  padding: 0 20px;
  font-size: 1.2rem;
}

/* Center stimulus vertically */
.stimulus {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 50vh;         /* middle of screen */
  font-size: 2.2rem;
  text-align: center;
  margin-top: 10vh;     /* spacing from labels */
}

button {
  font-size: 1.3rem !important;
  padding: 18px !important;
}