/* ===== Formula Accordion ===== */
.formula-accordion {
  border: 1.5px solid var(--line);
  border-radius: 10px;
  margin-top: 8px;
  overflow: hidden;
}

.formula-acc-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 12px;
  background: var(--paper-2);
  border: none;
  cursor: pointer;
  font: 500 12px/1 var(--font-body);
  color: var(--ink-soft);
  text-align: left;
  transition: background 0.15s, color 0.15s;
}

.formula-acc-trigger:hover {
  background: var(--accent-soft);
  color: var(--accent);
}

.formula-acc-trigger > svg:first-child {
  opacity: 0.6;
  flex-shrink: 0;
  color: var(--accent);
}

.formula-acc-label {
  flex: 1;
}

.formula-acc-chevron {
  flex-shrink: 0;
  transition: transform 0.22s cubic-bezier(.4,0,.2,1);
  color: var(--muted);
}

.formula-accordion.open .formula-acc-chevron {
  transform: rotate(180deg);
}

.formula-accordion.open .formula-acc-trigger {
  background: var(--accent-soft);
  color: var(--accent);
  border-bottom: 1.5px solid #C4B5FD;
}

.formula-accordion.open .formula-acc-trigger > svg:first-child {
  opacity: 1;
}

/* Toolbar — NASCOSTA di default, VISIBILE quando accordion è open */
.formula-toolbar {
  display: none;
  flex-wrap: wrap;
  align-items: flex-start;
  gap: 5px;
  padding: 10px 12px 12px;
  background: #F5F3FF;
}

.formula-accordion.open .formula-toolbar {
  display: flex;
}

/* Pulsanti simbolo */
.formula-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 32px;
  height: 28px;
  padding: 0 8px;
  background: #FFFFFF;
  border: 1.5px solid #C4B5FD;
  border-radius: 6px;
  font-size: 13px;
  font-family: var(--font-mono, "JetBrains Mono", monospace);
  color: #3730A3;
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s, transform 0.08s;
  user-select: none;
  white-space: nowrap;
}

.formula-btn:hover {
  background: #DDD6FE;
  border-color: #7C3AED;
  color: #4C1D95;
}

.formula-btn:active {
  transform: scale(0.93);
  background: #4338CA;
  color: #fff;
  border-color: #4338CA;
}

/* ===== KaTeX Live Preview ===== */
.formula-preview-wrap {
  margin-top: 6px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 10px 14px;
  background: var(--gold-soft);
  border: 1.5px solid #C4B5FD;
  border-radius: 10px;
  font-size: 15px;
  line-height: 1.7;
  overflow-x: auto;
}

.formula-preview-wrap.hidden { display: none; }

.formula-preview-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: #B45309;
  opacity: 0.8;
}

.formula-preview-content {
  color: var(--ink);
  overflow-x: auto;
}

.formula-hint {
  margin-top: 4px;
  font-size: 11px;
  color: var(--muted);
  line-height: 1.5;
}

/* ===== AI badge in footer ===== */
.ai-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--accent, #4338CA);
  background: rgba(67,56,202,0.08);
  border: 1px solid rgba(67,56,202,0.2);
  border-radius: 999px;
  padding: 2px 8px 2px 6px;
  white-space: nowrap;
}
.ai-badge svg { opacity: 0.7; }