/* ── ABOUT PAGE ─────────────────────────────────────────────
   Cover, principle cards, source bibliography, page index.
   ──────────────────────────────────────────────────────────── */

/* ── COVER FRAME ─────────────────────────────────────────── */
.cover {
  background: var(--bg-header);
  color: #fff;
  padding: 64px;
  margin-bottom: 48px;
  display: flex;
  gap: 64px;
  align-items: flex-start;
  min-height: 320px;
}
.cover-left { flex: 1; }
.cover-eyebrow {
  font-size: var(--type-label-size); font-weight: 600; letter-spacing: 0.12em;
  text-transform: uppercase; color: rgba(255,255,255,0.45);
  margin-bottom: 16px;
}
.cover-title {
  font-size: 40px; font-weight: 700; line-height: 1.15;
  margin-bottom: 12px; letter-spacing: -0.01em;
}
.cover-version {
  font-family: var(--font-mono);
  font-size: 12px; color: rgba(255,255,255,0.4);
  margin-bottom: 32px;
}
.cover-desc {
  font-size: 14px; line-height: 1.7; color: rgba(255,255,255,0.7);
  max-width: 480px;
}
.cover-right { width: 280px; flex-shrink: 0; }
.cover-stat {
  border-left: 2px solid rgba(255,255,255,0.15);
  padding: 12px 0 12px 20px;
  margin-bottom: 8px;
}
.cover-stat-val { font-size: var(--type-page-title-size); font-weight: var(--type-page-title-weight); line-height: 1; margin-bottom: 4px; }
.cover-stat-lbl { font-size: var(--type-label-size); color: rgba(255,255,255,0.45); letter-spacing: 0.06em; text-transform: uppercase; }

/* ── PRINCIPLE GRID ─────────────────────────────────────── */
.principle-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px;
}

/* ── PRINCIPLE CARD ──────────────────────────────────────── */
.principle-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  padding: 24px;
}
.principle-number {
  font-family: var(--font-mono);
  font-size: var(--type-body-size); color: var(--text-3); margin-bottom: 8px;
}
.principle-title {
  font-size: var(--type-heading-section-size); font-weight: var(--type-heading-section-weight); color: var(--text-1);
  margin-bottom: 8px; line-height: 1.3;
}
.principle-formula {
  font-family: var(--font-mono);
  font-size: var(--type-body-size); color: var(--cobalt-hi);
  background: #f0f3f8;
  padding: 6px 10px; margin-bottom: 12px;
  display: inline-block;
}
.principle-body {
  font-size: var(--type-heading-section-size); color: var(--text-2); line-height: 1.65;
}
.principle-rule {
  margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--border);
  font-size: var(--type-label-size); color: var(--text-3); line-height: 1.5;
}
.principle-rule strong { color: var(--text-2); font-weight: 600; }

/* ── CLICKABLE PRINCIPLE CARD ──────────────────────────────── */
.principle-card--clickable { cursor: pointer; transition: border-color 0.15s; }
.principle-card--clickable:hover { border-color: var(--bar-main); }
.principle-cta {
  margin-top: 12px;
  font-family: var(--font-mono); font-size: var(--type-annotation-size);
  color: var(--cobalt-hi); letter-spacing: 0.02em;
}

/* ── MODAL ──────────────────────────────────────────────────── */
.modal-overlay {
  display: none; position: fixed; inset: 0; z-index: 2000;
  background: rgba(26,25,23,0.55);
  backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px);
  overflow-y: auto; padding: 40px 24px;
}
.modal-overlay.modal--open {
  display: flex; justify-content: center; align-items: flex-start;
  animation: overlayFadeIn 0.25s ease;
}
.modal-overlay.modal--open .modal {
  animation: modalSlideUp 0.3s ease forwards;
}
@keyframes overlayFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}
@keyframes modalSlideUp {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}
.modal {
  background: var(--bg-surface); border: 1px solid var(--border);
  max-width: 720px; width: 100%; padding: 40px;
  position: relative;
}
.modal-close {
  position: absolute; top: 16px; right: 16px;
  background: none; border: none; cursor: pointer;
  font-size: 18px; color: var(--text-3); line-height: 1;
}
.modal-close:hover { color: var(--text-1); }
.modal-eyebrow {
  font-family: var(--font-mono); font-size: var(--type-label-size);
  color: var(--text-3); text-transform: uppercase; letter-spacing: 0.1em;
  margin-bottom: 8px;
}
.modal-title {
  font-size: var(--type-page-title-size); font-weight: var(--type-page-title-weight);
  color: var(--text-1); margin-bottom: 8px;
}
.modal-formula {
  font-family: var(--font-mono); font-size: var(--type-body-size);
  color: var(--cobalt-hi); background: #f0f3f8;
  padding: 8px 12px; margin-bottom: 32px; display: inline-block;
}

/* ── MODAL SECTIONS ────────────────────────────────────────── */
.modal-section { margin-bottom: 28px; }
.modal-section h3 {
  font-size: var(--type-heading-section-size); font-weight: var(--type-heading-section-weight);
  color: var(--text-1); margin-bottom: 8px;
  padding-bottom: 6px; border-bottom: 1px solid var(--border);
}
.modal-section p {
  font-size: var(--type-body-size); color: var(--text-2);
  line-height: 1.7; margin-bottom: 8px;
}
.modal-section p strong { color: var(--text-1); }
.modal-source {
  font-size: var(--type-annotation-size); font-family: var(--font-mono);
  color: var(--text-3); margin-top: 4px;
}

/* ── MODAL LIST ────────────────────────────────────────────── */
.modal-list {
  list-style: decimal; padding-left: 24px;
  font-size: var(--type-body-size); color: var(--text-2); line-height: 1.7;
}
.modal-list li {
  padding: 8px 0;
  border-bottom: 1px solid var(--bg-table-alt);
}
.modal-list li::marker {
  font-family: var(--font-mono); font-weight: 500;
  color: var(--cobalt-hi);
}
.modal-list li strong { color: var(--text-1); }

/* ── MODAL GRID ────────────────────────────────────────────── */
.modal-grid {
  display: grid; grid-template-columns: 1fr 1fr; gap: 12px;
}
.modal-item {
  font-size: var(--type-body-size); color: var(--text-2); line-height: 1.6;
  padding: 12px; background: var(--bg-page); border: 1px solid var(--border);
}
.modal-item strong { color: var(--text-1); display: block; margin-bottom: 2px; }

/* ── MODAL QUOTES ──────────────────────────────────────────── */
.modal-section--quotes blockquote {
  font-size: var(--type-body-size); font-style: italic;
  color: var(--text-2); line-height: 1.6;
  border-left: 2px solid var(--cobalt-hi); padding: 8px 0 8px 16px;
  margin: 0 0 12px 0;
}

/* ── MODAL LINKS ───────────────────────────────────────────── */
.modal-links {
  display: flex; flex-direction: column; gap: 8px;
  font-size: var(--type-body-size); color: var(--text-2); line-height: 1.6;
}
.modal-links a {
  color: var(--cobalt-hi); text-decoration: none; font-weight: 500;
}
.modal-links a:hover { text-decoration: underline; }

/* ── PAGE INDEX ──────────────────────────────────────────── */
.page-index {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
}
a.page-card {
  text-decoration: none; color: inherit; display: block;
}
.page-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  padding: 20px;
  transition: border-color 0.15s;
}
.page-card:hover {
  border-color: var(--bar-main);
}
.page-card-num {
  font-family: var(--font-mono);
  font-size: var(--type-label-size); color: var(--text-3); margin-bottom: 6px;
}
.page-card-name { font-size: var(--type-nav-size); font-weight: var(--type-heading-panel-weight); margin-bottom: 6px; }
.page-card-desc { font-size: var(--type-label-size); color: var(--text-2); line-height: 1.5; }

/* ── LARGE (≥1024px) ─────────────────────────────────────── */
@media (min-width: 1024px) {
  .cover { padding: 64px; gap: 64px; }
  .page-index { grid-template-columns: repeat(3, 1fr); }
}

/* ── MEDIUM (640px – 1023px) ─────────────────────────────── */
@media (min-width: 640px) and (max-width: 1023px) {
  .cover { padding: 40px; gap: 40px; flex-direction: column; }
  .cover-right { width: 100%; display: flex; gap: 16px; flex-wrap: wrap; }
  .cover-stat { flex: 1; min-width: 120px; }
  .cover-title { font-size: 32px; }
  .principle-grid { grid-template-columns: repeat(2, 1fr); }
  .page-index { grid-template-columns: repeat(2, 1fr); }
}

/* ── SMALL (<640px) ──────────────────────────────────────── */
@media (max-width: 639px) {
  .cover { flex-direction: column; padding: 24px; gap: 24px; min-height: auto; }
  .cover-title { font-size: 24px; }
  .cover-desc { font-size: 13px; }
  .cover-right { width: 100%; }
  .cover-stat-val { font-size: 22px; }
  .principle-grid { grid-template-columns: 1fr; }
  .page-index { grid-template-columns: 1fr; }
  .modal-overlay { padding: 16px; }
  .modal { padding: 24px; }
  .modal-title { font-size: 22px; }
  .modal-grid { grid-template-columns: 1fr; }
}