.title {
    text-align: center;
}

.question-text {
    font-size: 25px;
}

.answer {
    display: none;
}

.container {
  width: auto;
  max-width: 680px;
  padding: 0 15px;
}

.difficulty {
    margin: 10px;
}

.vertical-nav {
    position: fixed;
    right: 0;
    writing-mode: vertical-rl;
    text-orientation: mixed;
}

.thin-border {
    border-width: 0.15em;
}