.about-main {
  min-height: calc(100vh - var(--header-h) - 6rem);
}

.about-inner {
  max-width: 68ch;
  margin: 0 auto;
  padding: 3rem 1.5rem 4rem;
}

.about-label {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.4rem;
}

.about-title {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  font-weight: normal;
  margin: 0 0 0.4rem;
  line-height: 1.15;
}

.about-author {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  font-style: italic;
  color: var(--text-muted);
  margin: 0 0 2.5rem;
}

.about-body {
  font-size: 1rem;
  line-height: 1.75;
  color: var(--text);
}

.accordion {
  border-bottom: 1px solid var(--border);
  transition: border-color 0.3s ease;
}

.accordion:first-of-type {
  border-top: 1px solid var(--border);
}

.accordion-summary {
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.6rem;
  padding: 1.1rem 0;
  cursor: pointer;
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: normal;
  color: var(--text);
  user-select: none;
  transition: color 0.2s ease;
}

.accordion-summary::-webkit-details-marker { display: none; }

.accordion-summary::after {
  content: '+';
  font-family: var(--font-sans);
  font-size: 1.3rem;
  font-weight: 300;
  color: var(--text-muted);
  line-height: 1;
  flex-shrink: 0;
  transition: transform 0.25s ease, color 0.2s ease;
}

.accordion[open] > .accordion-summary::after {
  transform: rotate(45deg);
  color: var(--text);
}

.accordion-summary:hover {
  color: var(--accent);
}

.accordion-body {
  overflow: hidden;
  max-height: 0;
  opacity: 0;
  transition: max-height 0.38s ease, opacity 0.28s ease;
}

.accordion-body-inner {
  padding-bottom: 1.25rem;
  line-height: 1.75;
  color: var(--text);
  font-family: var(--font-serif);
}

.section-subhead {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-weight: bold;
  color: var(--text);
  margin: 1.75rem 0 0.5rem;
  letter-spacing: -0.01em;
}

.accordion-body-inner p {
  margin: 0 0 1rem;
}

.accordion-body-inner p:last-child {
  margin-bottom: 0;
}

.feature-list {
  padding-left: 1.25rem;
  margin: 0.5rem 0 1rem;
}

.feature-list li {
  margin-bottom: 0.5rem;
  line-height: 1.6;
}

.about-figure {
  margin: 1.5rem 0;
}

.about-img {
  width: 100%;
  max-width: 100%;
  border-radius: 4px;
  border: 1px solid var(--border);
  display: block;
}

.about-figure figcaption {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.5rem;
}

.motivation-figure {
  margin: 1.25rem 0;
}

.motivation-img {
  width: 100%;
  max-width: 100%;
  border-radius: 4px;
  border: 1px solid var(--border);
  display: block;
}

.motivation-figure figcaption {
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  margin-top: 0.5rem;
}

.accordion-no-toggle > .accordion-summary {
  cursor: default;
  pointer-events: none;
}

.accordion-no-toggle > .accordion-summary::after {
  display: none;
}

.backtest-table-wrap {
  overflow-x: auto;
  margin: 1.25rem 0;
}

.backtest-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--font-sans);
  font-size: 0.85rem;
}

.backtest-table th {
  text-align: left;
  padding: 0.45rem 0.75rem;
  border-bottom: 2px solid var(--border);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  white-space: nowrap;
}

.backtest-table td {
  padding: 0.45rem 0.75rem;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.backtest-table tbody tr:last-child td {
  border-bottom: none;
}

.td-better { color: #4a9e6b; font-weight: 600; }
.td-worse  { color: var(--text-muted); }

.coming-soon {
  font-family: var(--font-sans);
  font-size: 0.65rem;
  font-style: normal;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  border: 1px solid var(--border);
  padding: 0.15em 0.5em;
  border-radius: 2px;
  vertical-align: middle;
}