/* Mentor — strategic sounding board */
:root {
  --bg: #0f1115;
  --bg-elev: #161922;
  --bg-soft: #1c202b;
  --border: #2a2f3c;
  --border-soft: #1f2330;
  --text: #e8ebf2;
  --text-dim: #a3aab9;
  --text-faint: #6c7384;
  --accent: #d4a256;
  --accent-soft: #b08643;
  --danger: #d86c5e;
  --danger-soft: rgba(216, 108, 94, 0.12);
  --success: #6db380;
  --info: #7eb8c4;
  --serif: ui-serif, Georgia, Cambria, "Times New Roman", Times, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --maxw: 900px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* Layout */
.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--bg-elev);
  position: sticky;
  top: 0;
  z-index: 10;
}
.site-header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 14px 22px;
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
}
.brand {
  font-family: var(--serif);
  font-size: 22px;
  letter-spacing: 0.5px;
  color: var(--text);
  font-weight: 600;
}
.brand:hover { text-decoration: none; color: var(--accent); }
.brand .dot { color: var(--accent); }
nav.primary {
  display: flex;
  gap: 18px;
  flex: 1;
  flex-wrap: wrap;
}
nav.primary a {
  color: var(--text-dim);
  font-size: 14px;
  padding: 4px 0;
}
nav.primary a:hover, nav.primary a.active {
  color: var(--text);
  text-decoration: none;
  border-bottom: 1px solid var(--accent);
}

main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 32px 22px 80px;
}

.site-footer {
  max-width: var(--maxw);
  margin: 60px auto 30px;
  padding: 20px 22px;
  border-top: 1px solid var(--border-soft);
  color: var(--text-faint);
  font-size: 13px;
}

/* Typography */
h1 {
  font-family: var(--serif);
  font-size: 36px;
  font-weight: 600;
  letter-spacing: -0.5px;
  margin: 0 0 6px;
  line-height: 1.2;
}
h2 {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  margin: 32px 0 10px;
}
h3 {
  font-size: 14px;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--text-dim);
  margin: 24px 0 8px;
  font-weight: 600;
}
p { margin: 0 0 14px; }
.lede {
  font-family: var(--serif);
  font-size: 19px;
  color: var(--text-dim);
  line-height: 1.5;
  margin-bottom: 28px;
}

/* Cards */
.card {
  background: var(--bg-elev);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  padding: 18px 20px;
  margin: 0 0 14px;
  transition: border-color 0.15s, transform 0.15s;
}
.card:hover {
  border-color: var(--border);
}
.card a { color: inherit; }
.card a:hover { text-decoration: none; }

.card-title {
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 600;
  margin: 0 0 6px;
  color: var(--text);
}
.card-meta {
  font-size: 12px;
  color: var(--text-faint);
  letter-spacing: 0.4px;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.card-essence {
  color: var(--text-dim);
  font-size: 15px;
  margin: 0 0 10px;
}

.tag {
  display: inline-block;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  background: var(--bg-soft);
  color: var(--text-dim);
  padding: 3px 9px;
  margin: 2px 4px 2px 0;
  border-radius: 999px;
  border: 1px solid var(--border-soft);
}
.tag:hover {
  background: var(--border);
  color: var(--text);
  text-decoration: none;
  cursor: pointer;
}
.tag.active {
  background: var(--accent);
  color: var(--bg);
  border-color: var(--accent);
}

/* Principle detail */
.principle-detail h1 .num {
  color: var(--text-faint);
  font-size: 0.6em;
  margin-right: 12px;
  font-variant-numeric: tabular-nums;
}
.principle-section {
  margin: 22px 0;
}
.principle-section.defensive {
  border-left: 3px solid var(--accent);
  padding-left: 18px;
  background: rgba(212, 162, 86, 0.04);
  padding-top: 12px;
  padding-bottom: 12px;
  border-radius: 0 4px 4px 0;
}
.principle-section.red-flags {
  border-left: 3px solid var(--danger);
  padding-left: 18px;
  background: var(--danger-soft);
  padding-top: 12px;
  padding-bottom: 12px;
  border-radius: 0 4px 4px 0;
}
.principle-section ul {
  margin: 6px 0 0 0;
  padding-left: 22px;
}
.principle-section li {
  margin-bottom: 6px;
  color: var(--text);
}
.principle-section.red-flags li {
  color: var(--text);
}
.example, .reversal {
  font-family: var(--serif);
  color: var(--text-dim);
  font-size: 15px;
  line-height: 1.6;
}

/* Inputs */
input[type="text"], input[type="search"], textarea {
  width: 100%;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 12px 14px;
  font-size: 16px;
  font-family: inherit;
  border-radius: 6px;
}
input[type="text"]:focus, input[type="search"]:focus, textarea:focus {
  outline: none;
  border-color: var(--accent);
}
textarea {
  resize: vertical;
  min-height: 90px;
}

button, .btn {
  background: var(--accent);
  color: var(--bg);
  border: 0;
  padding: 10px 18px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  border-radius: 6px;
  cursor: pointer;
  font-family: inherit;
}
button:hover, .btn:hover { background: var(--accent-soft); }
button.ghost {
  background: transparent;
  color: var(--text-dim);
  border: 1px solid var(--border);
}
button.ghost:hover {
  color: var(--text);
  border-color: var(--text-dim);
}

/* Mode picker on home */
.mode-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 32px 0;
}
.mode-card {
  display: block;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 24px 22px;
  color: var(--text);
  transition: border-color 0.15s, background 0.15s;
}
.mode-card:hover {
  border-color: var(--accent);
  background: var(--bg-soft);
  text-decoration: none;
}
.mode-card-title {
  font-family: var(--serif);
  font-size: 22px;
  margin-bottom: 6px;
  color: var(--text);
}
.mode-card-desc {
  color: var(--text-dim);
  font-size: 14px;
}

/* Stats row on home */
.stats {
  display: flex;
  gap: 32px;
  flex-wrap: wrap;
  border-top: 1px solid var(--border-soft);
  border-bottom: 1px solid var(--border-soft);
  padding: 14px 0;
  margin: 30px 0;
  font-size: 13px;
  color: var(--text-faint);
}
.stat .num {
  font-family: var(--serif);
  font-size: 24px;
  color: var(--text);
  display: block;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
}

/* Filter row */
.filters {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 16px 0 26px;
  padding: 12px;
  background: var(--bg-elev);
  border-radius: 8px;
  border: 1px solid var(--border-soft);
}
.filters .label {
  font-size: 12px;
  text-transform: uppercase;
  color: var(--text-faint);
  letter-spacing: 0.6px;
  align-self: center;
  margin-right: 6px;
}

/* Result count */
.result-count {
  color: var(--text-faint);
  font-size: 13px;
  margin-bottom: 14px;
}

/* Loading / empty */
.loading {
  color: var(--text-faint);
  font-style: italic;
  padding: 20px 0;
}

/* Situation tagger results emphasis */
.situation-results .card {
  border-left: 3px solid var(--accent);
}
.situation-results .match-score {
  font-size: 11px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  font-weight: 600;
  margin-bottom: 4px;
}

/* Cross-references */
.related-list a {
  display: inline-block;
  margin: 4px 8px 4px 0;
  font-size: 13px;
  color: var(--text-dim);
  border: 1px solid var(--border-soft);
  padding: 3px 10px;
  border-radius: 4px;
}
.related-list a:hover {
  color: var(--text);
  border-color: var(--accent);
  text-decoration: none;
}

/* === Flip cards (principles grid) === */
.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
  margin-bottom: 28px;
}

.flip-card {
  perspective: 1200px;
  height: 180px;
  cursor: pointer;
}
.flip-card-inner {
  position: relative;
  width: 100%;
  height: 100%;
  transition: transform 0.55s cubic-bezier(0.5, 0, 0.3, 1);
  transform-style: preserve-3d;
}
.flip-card.flipped .flip-card-inner {
  transform: rotateY(180deg);
}
.flip-card-front,
.flip-card-back {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: 8px;
  padding: 14px 16px;
  background: var(--bg-elev);
  border: 1px solid var(--border-soft);
  display: flex;
  flex-direction: column;
  transition: border-color 0.15s;
  overflow: hidden;
}
.flip-card:hover .flip-card-front,
.flip-card:hover .flip-card-back {
  border-color: var(--border);
}
.flip-card-back {
  transform: rotateY(180deg);
  background: var(--bg-soft);
  border-color: var(--accent-soft);
}
.flip-card-meta {
  font-size: 10px;
  color: var(--text-faint);
  letter-spacing: 0.7px;
  text-transform: uppercase;
  margin-bottom: 8px;
  font-variant-numeric: tabular-nums;
}
.flip-card-num {
  color: var(--accent);
  font-weight: 600;
  margin-right: 6px;
}
.flip-card-title {
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.25;
  font-weight: 600;
  color: var(--text);
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}
.flip-card-tags {
  margin-top: 10px;
  font-size: 10px;
  color: var(--text-faint);
  letter-spacing: 0.5px;
  text-transform: uppercase;
}
.flip-card-tags span:not(:last-child)::after {
  content: ' · ';
  opacity: 0.5;
}
.flip-card-essence {
  font-family: var(--serif);
  font-size: 14px;
  line-height: 1.45;
  color: var(--text);
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 6;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin: 0 0 10px;
}
.flip-card-open {
  font-size: 11px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.7px;
  font-weight: 600;
  align-self: flex-start;
  border: 1px solid var(--accent-soft);
  padding: 4px 10px;
  border-radius: 4px;
  background: transparent;
  cursor: pointer;
  font-family: inherit;
  text-decoration: none;
}
.flip-card-open:hover {
  background: var(--accent);
  color: var(--bg);
  text-decoration: none;
}
.flip-hint {
  position: absolute;
  bottom: 10px;
  right: 12px;
  font-size: 10px;
  color: var(--text-faint);
  opacity: 0.6;
  letter-spacing: 0.5px;
}

/* === Book sections (collapsible) === */
.book-section {
  margin: 0 0 4px;
  border-top: 1px solid var(--border-soft);
}
.book-section summary {
  list-style: none;
  cursor: pointer;
  padding: 18px 4px 14px;
  display: flex;
  align-items: baseline;
  gap: 14px;
  flex-wrap: wrap;
  user-select: none;
}
.book-section summary::-webkit-details-marker { display: none; }
.book-section summary::marker { display: none; }
.book-section summary:hover .book-name {
  color: var(--accent);
}
.book-section summary .chev {
  font-size: 11px;
  color: var(--text-faint);
  display: inline-block;
  width: 12px;
  transition: transform 0.18s;
}
.book-section[open] summary .chev {
  transform: rotate(90deg);
}
.book-section .book-name {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  color: var(--text);
  margin: 0;
  transition: color 0.15s;
}
.book-section .book-byline {
  color: var(--text-faint);
  font-size: 13px;
}
.book-section .book-count {
  color: var(--text-faint);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  margin-left: auto;
}
.book-section .principles-grid {
  margin-top: 4px;
  padding-bottom: 18px;
}

/* Action row above sections */
.list-actions {
  display: flex;
  gap: 10px;
  align-items: center;
  margin: 6px 0 18px;
  flex-wrap: wrap;
}
.pill-btn {
  background: transparent;
  color: var(--text-dim);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 12px;
  cursor: pointer;
  font-family: inherit;
  letter-spacing: 0.4px;
  text-transform: none;
  font-weight: 400;
}
.pill-btn:hover {
  color: var(--text);
  border-color: var(--accent);
  background: transparent;
}

/* === Stacks === */
.stacks-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
  margin-bottom: 32px;
}
.stack-card {
  display: block;
  background: var(--bg-elev);
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  padding: 20px;
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s;
  position: relative;
}
.stack-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 10px;
  pointer-events: none;
  background: linear-gradient(135deg, rgba(212, 162, 86, 0.05), transparent 40%);
}
.stack-card:hover {
  border-color: var(--accent);
  text-decoration: none;
  transform: translateY(-1px);
}
.stack-card-meta {
  font-size: 11px;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
  margin-bottom: 10px;
}
.stack-card-title {
  font-family: var(--serif);
  font-size: 20px;
  font-weight: 600;
  line-height: 1.25;
  margin: 0 0 10px;
  color: var(--text);
}
.stack-card-summary {
  color: var(--text-dim);
  font-size: 14px;
  line-height: 1.5;
  margin-bottom: 14px;
}
.stack-card-foot {
  display: flex;
  gap: 8px;
  font-size: 12px;
  color: var(--text-faint);
  letter-spacing: 0.4px;
  text-transform: uppercase;
}

/* Stack detail */
.stack-detail h1 .num { /* unused but parallel to principle-detail */ }
.stack-steps {
  margin-top: 8px;
}
.stack-step {
  display: flex;
  gap: 18px;
  padding: 18px 0;
  border-bottom: 1px solid var(--border-soft);
}
.stack-step:last-child { border-bottom: 0; }
.stack-step-num {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent);
  color: var(--bg);
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: center;
  font-variant-numeric: tabular-nums;
  font-size: 15px;
}
.stack-step-body {
  flex: 1;
  min-width: 0;
}
.stack-step-meta {
  font-size: 11px;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 0.6px;
  margin-bottom: 6px;
}
.stack-step-role {
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.4;
  color: var(--text);
  margin-bottom: 8px;
  border-left: 2px solid var(--accent);
  padding-left: 12px;
}
.stack-step-essence {
  color: var(--text-dim);
  font-size: 14px;
  line-height: 1.5;
  margin-bottom: 10px;
}

/* === Books grid + book detail page === */
.books-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
  margin-bottom: 28px;
}
.book-card {
  display: block;
  background: var(--bg-elev);
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  padding: 20px;
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.15s, transform 0.15s, background 0.15s;
}
.book-card:hover {
  border-color: var(--accent);
  background: var(--bg-soft);
  text-decoration: none;
  transform: translateY(-1px);
}
.book-card-meta {
  font-size: 11px;
  color: var(--text-faint);
  letter-spacing: 0.6px;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.book-card-title {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: 12px;
  color: var(--text);
}
.book-card-foot {
  font-size: 12px;
  color: var(--accent);
  letter-spacing: 0.5px;
  text-transform: uppercase;
  font-weight: 600;
  margin-bottom: 10px;
}
.book-card-preview {
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.4;
  font-family: var(--serif);
  font-style: italic;
}

.reading-time-banner {
  display: flex;
  align-items: center;
  gap: 10px;
  background: rgba(212, 162, 86, 0.08);
  border: 1px solid var(--accent-soft);
  border-radius: 6px;
  padding: 10px 14px;
  margin: 10px 0 22px;
  color: var(--accent);
  font-size: 13px;
  letter-spacing: 0.4px;
  text-transform: uppercase;
  font-weight: 600;
}

.book-summary {
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.65;
  color: var(--text);
}
.book-summary p { margin: 0 0 14px; }
.book-summary p:first-child { font-size: 18px; color: var(--text); }
.book-summary strong { color: var(--text); font-weight: 600; }
.book-summary em { color: var(--text-dim); font-style: italic; }
.book-summary ul { margin: 10px 0 18px; padding-left: 24px; }
.book-summary li { margin-bottom: 8px; line-height: 1.5; }
.book-summary li strong { color: var(--accent); }

/* Mobile */
@media (max-width: 700px) {
  /* Horizontal-scrolling nav so the 7 links fit on narrow screens without wrapping */
  .site-header-inner {
    padding: 10px 14px;
    gap: 12px;
    flex-wrap: nowrap;
    overflow: hidden;
  }
  nav.primary {
    overflow-x: auto;
    flex-wrap: nowrap;
    -webkit-overflow-scrolling: touch;
    gap: 16px;
    font-size: 13px;
    padding-bottom: 2px;
    /* hide scrollbar */
    scrollbar-width: none;
  }
  nav.primary::-webkit-scrollbar { display: none; }
  nav.primary a { white-space: nowrap; flex-shrink: 0; }
}

@media (max-width: 600px) {
  h1 { font-size: 26px; }
  main { padding: 22px 16px 60px; }
  .lede { font-size: 17px; }
  .principles-grid { grid-template-columns: repeat(auto-fill, minmax(170px, 1fr)); gap: 10px; }
  .flip-card { height: 156px; }
  .flip-card-title { font-size: 15px; }
  .flip-card-front, .flip-card-back { padding: 12px 13px; }
  .stack-step { gap: 12px; padding: 14px 0; }
  .stack-step-num { width: 30px; height: 30px; font-size: 13px; }
  .stack-step-role { font-size: 15px; padding-left: 10px; }
  .book-summary { font-size: 16px; line-height: 1.6; }
  .book-card { padding: 16px; }
  .book-card-title { font-size: 19px; }
  .stacks-grid, .books-grid { grid-template-columns: 1fr; }
  .filters { padding: 10px; }
  .tag { font-size: 10.5px; padding: 3px 8px; }
}

/* Concepts */
.concept-sources { display: flex; flex-direction: column; gap: 14px; }
.concept-source {
  border-left: 3px solid var(--rule, #2a2a2a);
  padding: 8px 0 8px 14px;
}
.concept-source-title { font-size: 13.5px; margin-bottom: 4px; }
.concept-source-title a { color: var(--text, #e7e7e7); text-decoration: none; border-bottom: 1px dotted var(--text-dim, #888); }
.concept-source-title a:hover { color: var(--accent, #d3a55b); border-bottom-color: var(--accent, #d3a55b); }
.concept-source-take { font-size: 14.5px; line-height: 1.55; color: var(--text-dim, #b8b8b8); }
.category-section { margin-bottom: 8px; }
.category-section summary { cursor: pointer; padding: 14px 0; border-bottom: 1px solid var(--rule, #2a2a2a); display: flex; align-items: baseline; gap: 14px; }
.category-section summary::-webkit-details-marker { display: none; }
.category-section summary::marker { display: none; }
.category-section summary .chev { display: inline-block; transition: transform 0.15s ease; font-size: 11px; color: var(--text-dim, #888); }
.category-section[open] summary .chev { transform: rotate(90deg); }
.category-section .category-name { font-size: 17px; font-weight: 600; flex: 0 0 auto; }
.category-section .category-desc { font-size: 13.5px; color: var(--text-dim, #888); flex: 1 1 auto; }
.category-section .category-count { font-size: 12.5px; color: var(--text-dim, #888); flex: 0 0 auto; }
.category-section .concepts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 14px;
  padding: 18px 0;
}