@font-face {
  font-family: 'DejaVu Sans';
  src: url('fonts/DejaVuSans.ttf') format('truetype');
  font-display: swap;
}

.interval-staff {
  width: 100%;
  max-width: 480px;
  height: auto;
}

.interval-character-top {
  max-width: 220px;
  margin-left: auto;
  margin-right: auto;
}

.interval-character--top {
  max-width: 160px;
}

.interval-character-top .btn {
  min-width: 180px;
}

.interval-checkbox {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.75rem;
  border-radius: 0.75rem;
  border: 1px solid rgba(240, 77, 55, 0.28);
  background: linear-gradient(135deg, rgba(240, 77, 55, 0.12), rgba(240, 77, 55, 0.04));
  color: var(--theme-darker);
  transition: background-color 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
  margin: 0.15rem 0;
}

.interval-checkbox:hover,
.interval-checkbox:focus-within {
  background: linear-gradient(135deg, rgba(240, 77, 55, 0.16), rgba(240, 77, 55, 0.08));
  border-color: rgba(240, 77, 55, 0.45);
  box-shadow: 0 0 0 3px rgba(240, 77, 55, 0.16);
}

.interval-checkbox.is-checked {
  background: linear-gradient(135deg, rgba(240, 77, 55, 0.2), rgba(240, 77, 55, 0.1));
  border-color: rgba(240, 77, 55, 0.6);
  color: var(--theme-darker);
}

.interval-checkbox input[type="checkbox"] {
  width: 1.1rem;
  height: 1.1rem;
  accent-color: var(--theme-special);
}

.interval-checkbox input[type="checkbox"]:checked + span {
  font-weight: 600;
}

.interval-checkbox span {
  font-weight: 500;
}

.interval-checkbox-grid .col {
  padding-top: 0.15rem;
  padding-bottom: 0.15rem;
}

.interval-selection-section {
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}


.btn-interval-primary {
  background-color: #fff;
  border: 1.5px solid rgba(240, 77, 55, 0.45);
  color: var(--theme-darker);
  font-weight: 600;
}

.btn-interval-primary:hover:not(:disabled) {
  background-color: rgba(240, 77, 55, 0.12);
  border-color: rgba(240, 77, 55, 0.55);
  color: var(--theme-darker);
}

.btn-interval-primary:disabled {
  background-color: rgba(233, 236, 239, 0.65);
  border-color: rgba(233, 236, 239, 0.9);
  color: rgba(33, 37, 41, 0.4);
}

.btn-interval-secondary {
  background-color: #fff;
  border: 1px solid rgba(33, 37, 41, 0.18);
  color: rgba(33, 37, 41, 0.85);
  font-weight: 500;
}

.btn-interval-secondary:hover,
.btn-interval-secondary:focus {
  background-color: rgba(240, 77, 55, 0.1);
  border-color: rgba(240, 77, 55, 0.3);
  color: var(--theme-darker);
}

.btn-interval-play {
  background-color: #fff;
  border: 1.5px solid rgba(240, 77, 55, 0.4);
  color: var(--theme-special);
  font-weight: 600;
  padding: 0.75rem 2.5rem;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}

.btn-interval-play:hover {
  background-color: rgba(240, 77, 55, 0.08);
  border-color: rgba(240, 77, 55, 0.5);
  color: var(--theme-darker);
}

.btn-interval-toggle {
  border: 1px solid rgba(33, 37, 41, 0.18);
  background-color: #fff;
  color: rgba(33, 37, 41, 0.85);
  font-weight: 500;
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.btn-interval-toggle:hover {
  background-color: rgba(240, 77, 55, 0.08);
  color: var(--theme-darker);
}

.btn-check:checked + .btn-interval-toggle,
.btn-interval-toggle.active {
  background-color: rgba(240, 77, 55, 0.16);
  border-color: rgba(240, 77, 55, 0.42);
  color: var(--theme-darker);
  box-shadow: 0 0 0 0.2rem rgba(240, 77, 55, 0.15);
}

.interval-clef {
  font-size: 94px;
  fill: #212529;
  font-family: 'Noto Music', 'Bravura', 'DejaVu Sans', 'Arial Unicode MS', 'Segoe UI Symbol', serif;
  text-anchor: middle;
  dominant-baseline: middle;
}

.interval-accidental {
  font-size: 36px;
  fill: #212529;
  font-family: 'Bravura', 'Noto Music', 'DejaVu Sans', 'Arial Unicode MS', serif;
  text-anchor: middle;
  dominant-baseline: middle;
}

.interval-note {
  fill: #fff;
  stroke: #212529;
  stroke-width: 2;
}

.interval-ledger {
  stroke: #212529;
  stroke-width: 1.5;
  stroke-linecap: round;
}

#feedbackMessage.correct {
  color: var(--theme-special);
}

#feedbackMessage.incorrect {
  color: #a22020;
}

.interval-answer-btn {
  min-width: 150px;
  flex: 1 1 180px;
  border: 2px solid var(--theme-special);
  background-color: var(--theme-special);
  color: var(--theme-lightest);
  font-weight: 600;
  transition: background-color 0.2s ease, color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease;
}

.interval-answer-btn:hover:not(:disabled) {
  background-color: var(--theme-darker);
  border-color: var(--theme-darker);
  color: var(--theme-lightest);
  transform: translateY(-1px);
  box-shadow: 0 12px 22px rgba(240, 77, 55, 0.18);
}

.interval-answer-btn:disabled {
  opacity: 0.85;
  cursor: not-allowed;
  transform: none;
}

.interval-answer-btn.correct {
  box-shadow: 0 14px 28px rgba(240, 77, 55, 0.28);
}

.interval-answer-btn.incorrect {
  background-color: #f8d7da;
  border-color: #f8d7da;
  color: #842029;
  box-shadow: none;
}

.text-interval-score {
  color: var(--theme-special);
}

.interval-cta {
  max-width: 640px;
  white-space: normal;
}

.interval-character {
  max-width: 220px;
  width: 100%;
  height: auto;
}

.btn-interval-cta {
  background-color: rgba(240, 77, 55, 0.1);
  border: 2px solid rgba(240, 77, 55, 0.45);
  color: var(--theme-darker);
  font-weight: 600;
  padding: 0.75rem 2rem;
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.btn-interval-cta:hover {
  background-color: var(--theme-special);
  border-color: var(--theme-special);
  color: var(--theme-lightest);
  box-shadow: 0 12px 28px rgba(240, 77, 55, 0.22);
}

.interval-toggle-bar {
  border: 1px solid rgba(33, 37, 41, 0.15);
  border-radius: 0.85rem;
  padding: 0.85rem 1rem;
  background-color: #fff;
  width: 100%;
  max-width: 640px;
  margin-left: auto;
  margin-right: auto;
  box-shadow: 0 12px 28px rgba(15, 23, 42, 0.05);
}

.interval-question {
  font-size: 56px;
  fill: var(--theme-special);
  font-family: 'Nunito', 'Fredoka', 'DejaVu Sans', sans-serif;
  text-anchor: middle;
  dominant-baseline: middle;
}

@media (max-width: 767.98px) {
  .interval-toggle-bar {
    padding: 0.75rem;
  }

  .interval-character--top {
    max-width: 130px;
  }
}