.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  min-height: 48px;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 500;
  line-height: 1;
  transition: background-color var(--transition-fast),
              transform var(--transition-fast),
              box-shadow var(--transition-fast);
  box-shadow: var(--shadow-button);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn:active {
  transform: scale(0.97);
}

.btn:focus-visible {
  outline: 3px solid var(--color-accent);
  outline-offset: 3px;
}

.btn--accent {
  background-color: var(--color-know);
  color: var(--color-know-text);
}

.btn--accent:hover {
  background-color: var(--color-know-hover);
  color: #ffffff;
}

.btn--review {
  background-color: var(--color-review);
  color: var(--color-review-text);
}

.btn--review:hover {
  background-color: var(--color-review-hover);
  color: #ffffff;
}

.btn--sm {
  padding: 0.5rem 1.25rem;
  min-height: 40px;
  font-size: 0.9rem;
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-text-muted);
  box-shadow: none;
  border: 1px solid var(--color-border);
}

.btn--ghost:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}

.answer-buttons {
  display: flex;
  gap: var(--space-md);
  width: 100%;
  max-width: 420px;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
}

.answer-buttons.is-visible {
  opacity: 1;
  pointer-events: auto;
}

.answer-buttons .btn {
  flex: 1;
}

@media (max-width: 360px) {
  .answer-buttons {
    flex-direction: column;
  }
}

.btn--save {
  font-size: 0.875rem;
  padding: 0.5rem 1rem;
  min-height: 36px;
  gap: 5px;
  border-radius: var(--radius-sm);
  background-color: transparent;
  color: var(--color-text-muted);
  border: 1px solid var(--color-border);
  box-shadow: none;
}

.btn--save:hover {
  background-color: var(--color-bg);
  color: var(--color-text);
}