.link-channels-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;

  display: flex;
  align-items: center;
  justify-content: center;

  padding: var(--space-5);

  background: rgba(0, 0, 0, 0.5);

  animation: link-channels-fade-in var(--dur-base) var(--ease-standard);
}

@keyframes link-channels-fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

.link-channels-modal {
  width: 100%;
  max-width: 480px;
  max-height: 90vh;

  overflow-y: auto;

  animation: link-channels-scale-in var(--dur-base) var(--ease-standard);
}

@keyframes link-channels-scale-in {
  from {
    opacity: 0;
    transform: scale(0.96);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

.link-channels-modal__header {
  margin-bottom: var(--space-4);
}

.link-channels-modal__header h2 {
  margin: 0;

  font-size: var(--font-md);
  font-weight: var(--font-weight-semibold);
  color: var(--text-primary);
}

.link-channels-modal__header p {
  margin: var(--space-1) 0 0;

  font-size: var(--font-sm);
  line-height: 1.4;
  color: var(--text-muted);
}

/* Mode toggle */

.link-channels-modal__mode-toggle {
  display: inline-flex;

  padding: var(--space-1);
  margin-bottom: var(--space-5);

  background: var(--bg-panel);
  border: var(--border-width) solid var(--border-hairline);
  border-radius: var(--radius-sm);
}

.link-channels-modal__mode-btn {
  padding: var(--space-2) var(--space-4);

  background: transparent;
  color: var(--text-muted);

  border: none;
  border-radius: var(--radius-sm);

  font-family: var(--font-ui);
  font-size: var(--font-sm);
  font-weight: var(--font-weight-semibold);

  cursor: pointer;

  transition:
    background var(--dur-base) var(--ease-standard),
    color var(--dur-base) var(--ease-standard);
}

.link-channels-modal__mode-btn.is-active {
  background: var(--accent-brand);
  color: var(--bg-panel);
}

/* Triangular link matrix */

.link-matrix {
  display: grid;
  gap: var(--space-1);

  margin-bottom: var(--space-5);
}

.link-matrix__corner {
  width: var(--space-6);
}

.link-matrix__col-label,
.link-matrix__row-label {
  display: flex;
  align-items: center;
  justify-content: center;

  font-family: var(--font-mono);
  font-size: var(--font-sm);
  color: var(--text-muted);
}

.link-matrix__row-label {
  justify-content: flex-start;
  padding-right: var(--space-2);
}

.link-matrix__row {
  display: contents;
}

.link-matrix__cell {
  aspect-ratio: 1 / 1;
  min-width: 32px;

  border-radius: var(--radius-sm);
}

.link-matrix__cell--empty {
  background: transparent;
}

.link-matrix__cell--toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;

  background: var(--bg-panel);
  border: var(--border-width) solid var(--border-hairline);

  cursor: pointer;

  transition:
    background var(--dur-base) var(--ease-standard),
    border-color var(--dur-base) var(--ease-standard);
}

.link-matrix__cell--toggle:hover {
  border-color: var(--accent-brand);
}

.link-matrix__cell--toggle.is-active {
  background: var(--accent-brand);
  border-color: var(--accent-brand);
  cursor: default;
}

.link-matrix__cell--toggle:disabled:hover {
  border-color: var(--accent-brand);
}

/* A row whose channel is itself following another channel can't also
   lead others - its other tiles are locked rather than just inactive. */

.link-matrix__cell--unavailable {
  background: repeating-linear-gradient(
    45deg,
    var(--border-hairline),
    var(--border-hairline) 2px,
    transparent 2px,
    transparent 6px
  );
  border-color: var(--border-hairline);

  cursor: not-allowed;
}

.link-matrix__cell--unavailable:hover {
  border-color: var(--border-hairline);
}

/* Footer actions */

.link-channels-modal__actions {
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
}

@media (max-width: 600px) {
  .link-matrix__cell {
    min-width: 26px;
  }
}