html {
  font-size: 14px;
}

@media (min-width: 768px) {
  html {
    font-size: 16px;
  }
}

.btn:focus, .btn:active:focus, .btn-link.nav-link:focus, .form-control:focus, .form-check-input:focus {
  box-shadow: 0 0 0 0.1rem white, 0 0 0 0.25rem #258cfb;
}

html {
  position: relative;
  min-height: 100%;
}

body {
  margin-bottom: 60px;
}

.solution {
    color: green;
    font-style: italic;
}

.grammar-card {
    background-color: #fff;
    padding: 1em;
    border: 1px solid #ddd;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
}

.bg-success-subtle {
    background-color: #d4edda;
}

.bg-danger-subtle {
    background-color: #f8d7da;
}


.jp {
    font-size: 2.4rem;
    line-height: 1.4;
}

.en {
    font-size: 2.0rem;
    line-height: 1.4;
    filter: blur(8px);
    transition: filter .2s;
}

    .en.show {
        filter: none;
    }

ruby rt {
    visibility: hidden;
    font-size: .55em;
}

ruby:hover rt {
    visibility: visible;
}
/* on-hover furigana reveal */
.rules {
    display: none;
    border-top: 1px solid #dee2e6;
    margin-top: 1.5rem;
    padding-top: 1rem;
}

    .rules.show {
        display: block;
    }