/* Binaural Beats Frequency Calculator — pure-math bidirectional converter */

/* ── Tool grid + panels ── */
.tool-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
  margin-bottom: var(--space-xl);
}
.tool-panel {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
}
.panel-title {
  font-family: var(--font-display);
  font-size: var(--fs-base);
  color: var(--color-primary);
  margin: 0 0 var(--space-md);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.bbc-mode__intro {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  margin-bottom: var(--space-md);
  font-style: italic;
}

/* ── Inputs ── */
.input-group { margin-bottom: var(--space-md); }
.input-label {
  display: block;
  font-size: var(--fs-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xs);
  font-family: var(--font-mono);
}
.input-hint {
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  margin-top: 4px;
  font-style: italic;
}

.bbc-input-wrap {
  display: grid;
  grid-template-columns: 1fr 48px;
  align-items: stretch;
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.15s, box-shadow 0.15s;
}
.bbc-input-wrap:focus-within {
  border-color: var(--color-primary);
  box-shadow: 0 0 12px color-mix(in srgb, var(--color-primary) 25%, transparent);
}
.bbc-input {
  background: transparent;
  border: none;
  color: var(--color-secondary);
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-variant-numeric: tabular-nums;
  padding: 10px var(--space-md);
  outline: none;
  width: 100%;
  /* Hide spinner arrows on number inputs across browsers */
  -moz-appearance: textfield;
}
.bbc-input::-webkit-outer-spin-button,
.bbc-input::-webkit-inner-spin-button {
  -webkit-appearance: none;
  margin: 0;
}
.bbc-unit {
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  background: rgba(0, 255, 65, 0.05);
  border-left: 1px solid var(--color-border);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ── Result blocks ── */
.bbc-result-title {
  font-family: var(--font-display);
  font-size: var(--fs-sm);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: var(--space-lg) 0 var(--space-sm);
}
.bbc-result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
}
.bbc-result {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  text-align: center;
}
.bbc-result--left  { border-color: rgba(0, 255, 65, 0.45); }
.bbc-result--right { border-color: rgba(255, 119, 170, 0.45); }
.bbc-result__label {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.bbc-result__value {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--color-secondary);
  font-variant-numeric: tabular-nums;
  margin-top: 4px;
}
.bbc-result--left  .bbc-result__value { color: var(--color-primary); text-shadow: 0 0 10px rgba(0,255,65,0.45); }
.bbc-result--right .bbc-result__value { color: #ff77aa;             text-shadow: 0 0 10px rgba(255,119,170,0.45); }
.bbc-result__value--beat { color: var(--color-primary); text-shadow: 0 0 10px rgba(0,255,65,0.45); }
.bbc-result__sub {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  margin-top: 4px;
}

/* ── Brainwave-band card ── */
.bbc-band {
  background: var(--color-bg);
  border: 1px solid var(--color-primary);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  text-align: center;
  margin-bottom: var(--space-md);
  box-shadow: 0 0 14px color-mix(in srgb, var(--color-primary) 12%, transparent);
}
.bbc-band__label {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}
.bbc-band__value {
  font-family: var(--font-display);
  font-size: 1.5rem;
  font-weight: 700;
  margin: 4px 0 2px;
  transition: color 0.25s ease, text-shadow 0.25s ease;
}
.bbc-band__desc {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
}

.bbc-try-btn { width: 100%; }
.bbc-try-btn[disabled] { opacity: 0.5; cursor: not-allowed; }

/* ── Reference chart ── */
.bbc-chart-heading {
  text-align: center;
  margin: var(--space-xl) 0 var(--space-md);
  font-family: var(--font-display);
  color: var(--color-primary);
}
.bbc-chart {
  max-width: 1000px;
  margin: 0 auto var(--space-xl);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-bg);
}
.bbc-chart__row {
  display: grid;
  grid-template-columns: 130px 110px 1fr 1fr;
  gap: var(--space-md);
  padding: var(--space-md);
  border-bottom: 1px solid var(--color-border);
  font-family: var(--font-mono);
  font-size: var(--fs-sm);
  color: var(--color-text);
  border-left: 4px solid var(--band-color, transparent);
  line-height: 1.5;
}
.bbc-chart__row:last-child { border-bottom: none; }
.bbc-chart__head {
  background: var(--color-surface);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: var(--fs-xs);
  border-left-color: transparent;
}
.bbc-chart__band strong {
  font-family: var(--font-display);
  font-size: var(--fs-md);
  color: var(--band-color);
  letter-spacing: 0.03em;
}
.bbc-chart__range {
  color: var(--color-secondary);
  font-variant-numeric: tabular-nums;
  font-weight: 600;
}

/* ── Content / FAQ / Related (unchanged from other tools) ── */
.content-section {
  max-width: 800px;
  margin: 0 auto var(--space-lg);
  color: var(--color-text);
  line-height: 1.7;
}
.content-section h3 {
  color: var(--color-secondary);
  font-family: var(--font-display);
  margin-top: var(--space-lg);
  margin-bottom: var(--space-xs);
  font-size: var(--fs-md);
}
.content-section p { margin-bottom: var(--space-sm); }
.content-section ul { margin: var(--space-sm) 0 var(--space-sm) var(--space-lg); }
.content-section li { margin-bottom: 4px; }

.faq-list { max-width: 800px; margin: 0 auto; }
.faq-item {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-sm);
  overflow: hidden;
}
.faq-question {
  padding: var(--space-md);
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--color-text-bright);
}
.faq-question::-webkit-details-marker { display: none; }
.faq-question::after { content: '+'; color: var(--color-primary); font-size: 1.3em; font-weight: 700; }
details[open] .faq-question::after { content: '−'; }
.faq-answer {
  padding: 0 var(--space-md) var(--space-md);
  color: var(--color-text-muted);
  line-height: 1.75;
  border-top: 1px solid var(--color-border);
  padding-top: var(--space-sm);
}

.related-tools-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  max-width: 900px;
  margin: 0 auto;
}
.related-tool-card {
  display: block;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  text-decoration: none;
  transition: border-color 0.2s, transform 0.2s;
  text-align: left;
}
.related-tool-card:hover { border-color: var(--color-primary); transform: translateY(-2px); }
.related-tool-card__title {
  font-family: var(--font-display);
  font-size: var(--fs-sm);
  color: var(--color-primary);
  margin-bottom: var(--space-xs);
}
.related-tool-card__desc {
  font-size: var(--fs-xs);
  color: var(--color-text-muted);
  line-height: 1.5;
}

/* ── Responsive ── */
@media (max-width: 768px) {
  .tool-grid { grid-template-columns: 1fr; }
  .related-tools-grid { grid-template-columns: 1fr; }
  .bbc-result-grid { grid-template-columns: 1fr; }
  .bbc-chart__row {
    grid-template-columns: 1fr;
    gap: var(--space-xs);
    padding: var(--space-md);
  }
  .bbc-chart__head { display: none; }   /* column header collapses into per-cell labels below */
  /* Inline labels from data-label attributes so each cell still names
     itself when stacked vertically. The empty data-label on the Band
     cell keeps its visual prominence as the row's "headline". */
  .bbc-chart__row > [data-label]::before {
    content: attr(data-label) ': ';
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-size: var(--fs-xs);
    margin-right: 6px;
  }
  /* The Band cell already shows the colored band name prominently; drop
     its "Band:" prefix on mobile so it stays visually impactful. */
  .bbc-chart__row > .bbc-chart__band::before { content: none; }
}