.faq-page main > section { max-width: 1600px; margin: 0 auto; padding: var(--section-spacing) 2rem; }
.whitepaper-button-secondary { color: var(--text-primary); background: transparent; }
.whitepaper-button-secondary:hover { color: var(--canvas-bg); background: var(--text-primary); }
.faq-hero { min-height: min(900px, 100svh); }
.faq-hero h1 { max-width: 14ch; }
.faq-section, .faq-boundaries { scroll-margin-top: 4rem; border-top: 1px solid var(--grid-line); }
.faq-tools {
  display: grid;
  grid-template-columns: minmax(260px, 1fr) auto auto;
  gap: 1rem;
  align-items: end;
  margin: 4rem 0 2rem;
  padding: 1.25rem;
  border: 1px solid var(--panel-border);
  background: var(--panel-bg);
}
.faq-search { display: grid; gap: 0.55rem; min-width: 0; }
.faq-search > span, .faq-tool-label, .faq-results {
  color: var(--text-faint);
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  letter-spacing: var(--ls-wide);
  text-transform: uppercase;
}
.faq-search input {
  width: 100%;
  min-height: 3rem;
  padding: 0.75rem 0.9rem;
  border: 1px solid var(--panel-border);
  border-radius: 0;
  color: var(--text-primary);
  background: var(--panel-control-bg);
}
.faq-search input::placeholder { color: var(--text-faint); }
.faq-filter-group, .faq-open-group { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.faq-filter-group { align-items: center; }
.faq-tool-label { flex-basis: 100%; }
.faq-filter {
  min-height: 3rem;
  padding: 0.7rem 0.85rem;
  border: 1px solid var(--panel-border);
  color: var(--text-muted);
  background: var(--panel-control-bg);
  cursor: pointer;
}
.faq-filter:hover, .faq-filter.is-active {
  border-color: var(--text-primary);
  color: var(--canvas-bg);
  background: var(--text-primary);
}
.faq-results { grid-column: 1 / -1; margin: 0; }
.faq-list { border-top: 1px solid var(--panel-border); }
.faq-item { scroll-margin-top: 4.5rem; border-bottom: 1px solid var(--panel-border); }
.faq-item[hidden], .faq-empty[hidden] { display: none; }
.faq-item summary {
  display: grid;
  grid-template-columns: 4rem minmax(0, 1fr) 1.5rem;
  gap: 1rem;
  align-items: center;
  min-height: 7rem;
  padding: 1.25rem 0;
  cursor: pointer;
  list-style: none;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary:hover .faq-question { color: var(--text-primary); }
.faq-number {
  color: var(--text-faint);
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  letter-spacing: var(--ls-wide);
}
.faq-question {
  color: var(--text-muted);
  font-size: clamp(1.15rem, 2vw, 1.75rem);
  line-height: 1.35;
  transition: color 0.2s ease;
}
.faq-marker { position: relative; width: 1.25rem; height: 1.25rem; }
.faq-marker::before, .faq-marker::after {
  position: absolute;
  top: 50%;
  left: 0;
  width: 100%;
  height: 1px;
  content: "";
  background: var(--text-muted);
  transition: transform 0.2s ease;
}
.faq-marker::after { transform: rotate(90deg); }
.faq-item[open] .faq-marker::after { transform: rotate(0); }
.faq-item[open] .faq-question { color: var(--text-primary); }
.faq-answer-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0 0 2rem 5rem;
  border: 1px solid var(--panel-border);
  background: var(--panel-border);
}
.faq-page .faq-answer {
  min-width: 0;
  max-width: none;
  margin: 0;
  padding: clamp(1.25rem, 3vw, 2.5rem);
  background: var(--canvas-bg);
}
.faq-answer p { margin: 0 0 1rem; }
.faq-answer p:last-child { margin-bottom: 0; }
.faq-audience {
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: var(--fs-small);
  letter-spacing: var(--ls-wide);
  text-transform: uppercase;
}
.middle-diagram {
  min-width: 0;
  margin: 1rem 0 1.5rem;
  padding: 0.75rem;
  overflow-x: auto;
  border: 1px solid var(--panel-border);
  background: var(--panel-control-bg);
  scrollbar-color: var(--text-faint) transparent;
}
.middle-diagram svg {
  display: block;
  width: 100%;
  height: auto;
  min-width: 32rem;
}
.middle-diagram figcaption {
  margin-top: 0.6rem;
  color: var(--text-faint);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  line-height: 1.6;
}
.answer-expert { color: var(--text-muted); }
.faq-equation-card {
  min-width: 0;
  margin: 1.5rem 0;
  padding: 1rem;
  overflow-x: auto;
  border: 1px solid var(--panel-border);
  background: var(--panel-control-bg);
}
.faq-equation { min-width: max-content; font-size: clamp(0.72rem, 1.2vw, 1rem); }
.faq-equation-parameters { min-width: max-content; color: var(--text-muted); font-size: clamp(0.68rem, 1.5vw, 1rem); }
.faq-equation-card [data-status="pass"] { color: var(--text-muted); }
.faq-equation-card [data-status="fail"] { color: var(--accent); }
.faq-noscript, .faq-empty {
  padding: 1rem;
  border: 1px solid var(--panel-border);
  color: var(--text-muted);
}
.faq-page[data-audience-filter="middle"] .answer-expert,
.faq-page[data-audience-filter="expert"] .answer-middle { display: none; }
.faq-page[data-audience-filter="middle"] .faq-answer-grid,
.faq-page[data-audience-filter="expert"] .faq-answer-grid { grid-template-columns: 1fr; }

@media (max-width: 768px) {
  .faq-page main > section { padding-inline: 1rem; }
  .faq-tools { grid-template-columns: 1fr; align-items: stretch; }
  .faq-results { grid-column: 1; }
  .faq-open-group .btn { flex: 1; }
  .faq-item summary { grid-template-columns: 2.5rem minmax(0, 1fr) 1.25rem; gap: 0.75rem; min-height: 6rem; }
  .faq-answer-grid { grid-template-columns: 1fr; margin-left: 0; }
  .faq-page .faq-answer { padding: 1.25rem; }
  .middle-diagram { margin-inline: -0.25rem; padding: 0.6rem; }
  .middle-diagram svg { width: 100%; min-width: 0; max-width: 100%; }
}