/**
 * knowledge.css
 *
 * Design-system extension for the WaterBalanceTools knowledge platform
 * (Academy, Formula Library, Glossary, Reference, Methodology).
 *
 * Depends on style.css custom properties — always loaded AFTER style.css.
 * Never duplicates calculator styles; only adds new components.
 */

/* ── Two-column knowledge layout ────────────────────────────────────────────── */

.knowledge-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  align-items: start;
}

@media (min-width: 1024px) {
  .knowledge-layout {
    grid-template-columns: 240px 1fr;
    gap: 2.5rem;
  }
  .knowledge-sidebar {
    position: sticky;
    top: 1.5rem;
    max-height: calc(100vh - 3rem);
    overflow-y: auto;
  }
}

.knowledge-content {
  min-width: 0; /* prevent grid blowout */
}

/* ── Sidebar ─────────────────────────────────────────────────────────────────── */

.knowledge-sidebar {
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 1.25rem;
}
.knowledge-sidebar h3 {
  font-size: 11px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-secondary);
  margin: 0 0 0.6rem;
}
.knowledge-sidebar-section {
  margin-bottom: 1.25rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-soft);
}
.knowledge-sidebar-section:last-child {
  margin-bottom: 0;
  padding-bottom: 0;
  border-bottom: none;
}
.knowledge-sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.knowledge-sidebar li {
  margin: 0;
}
.knowledge-sidebar a {
  display: block;
  font-size: 13px;
  color: var(--text-secondary);
  text-decoration: none;
  padding: 0.3rem 0;
  line-height: 1.5;
  border-radius: 4px;
}
.knowledge-sidebar a:hover {
  color: var(--blue);
}
.knowledge-sidebar a.active {
  color: var(--blue);
  font-weight: var(--font-weight-medium);
}

/* ── Breadcrumb ──────────────────────────────────────────────────────────────── */

.breadcrumb {
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 0;
}
.breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.15rem;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 12px;
  color: var(--text-secondary);
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1rem;
  padding-right: 1rem;
}
@media (min-width: 820px) {
  .breadcrumb-list {
    padding-left: 1.5rem;
    padding-right: 1.5rem;
  }
}
.breadcrumb-list a {
  color: var(--text-secondary);
  text-decoration: none;
}
.breadcrumb-list a:hover {
  color: var(--blue);
  text-decoration: underline;
}
.breadcrumb-sep {
  color: var(--border-soft);
  user-select: none;
  padding: 0 0.1rem;
  font-size: 14px;
}
.breadcrumb-list li[aria-current="page"] {
  color: var(--text-primary);
  font-weight: var(--font-weight-medium);
}

/* ── Knowledge hero ──────────────────────────────────────────────────────────── */

.knowledge-hero {
  padding: 2rem 0 1.5rem;
}
.knowledge-hero-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}
.knowledge-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 11px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  padding: 0.25rem 0.6rem;
  border-radius: 100px;
  background: var(--blue-light);
  color: var(--blue);
  border: 1px solid rgba(14, 116, 144, 0.2);
}
.knowledge-badge--fundamentals  { background: #ecfdf5; color: #166534; border-color: rgba(22,101,52,0.2); }
.knowledge-badge--sanitizers    { background: #fff7ed; color: #9a3412; border-color: rgba(154,52,18,0.2); }
.knowledge-badge--testing       { background: #f0f9ff; color: #0369a1; border-color: rgba(3,105,161,0.2); }
.knowledge-badge--water-balance { background: var(--blue-light); color: var(--blue); border-color: rgba(14,116,144,0.2); }
.knowledge-badge--troubleshooting { background: #fef9c3; color: #713f12; border-color: rgba(113,63,18,0.2); }
.knowledge-badge--hot-tubs      { background: #fdf2f8; color: #86198f; border-color: rgba(134,25,143,0.2); }
.knowledge-badge--equipment     { background: #f8fafc; color: #475569; border-color: rgba(71,85,105,0.2); }
.knowledge-badge--vacation-rentals { background: #f0fdf4; color: #166534; border-color: rgba(22,101,52,0.2); }
.knowledge-badge--formula       { background: #eff6ff; color: #1d4ed8; border-color: rgba(29,78,216,0.2); }
.knowledge-badge--glossary      { background: #faf5ff; color: #7e22ce; border-color: rgba(126,34,206,0.2); }
.knowledge-badge--reference     { background: #fff1f2; color: #be123c; border-color: rgba(190,18,60,0.2); }

.knowledge-hero-reading {
  font-size: 12px;
  color: var(--text-secondary);
}
.knowledge-hero h1 {
  font-size: clamp(24px, 4vw, 36px);
  line-height: 1.2;
  margin: 0 0 0.75rem;
}
.knowledge-hero-summary {
  font-size: 17px;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0 0 1.25rem;
}
.knowledge-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: 1rem;
}
.knowledge-chip {
  display: inline-flex;
  align-items: center;
  font-size: 12px;
  font-weight: var(--font-weight-medium);
  padding: 0.3rem 0.7rem;
  border-radius: 100px;
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  color: var(--text-secondary);
  text-decoration: none;
  transition: background 0.15s, border-color 0.15s;
  cursor: pointer;
}
.knowledge-chip:hover {
  background: var(--blue-light);
  border-color: rgba(14,116,144,0.3);
  color: var(--blue);
  text-decoration: none;
}

/* ── Cards ───────────────────────────────────────────────────────────────────── */

.knowledge-card {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  background: var(--white);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 1.1rem 1.25rem;
  text-decoration: none;
  color: var(--text-primary);
  transition: border-color 0.15s, box-shadow 0.15s, transform 0.15s;
  box-shadow: var(--shadow);
}
.knowledge-card:hover {
  border-color: var(--blue-soft);
  box-shadow: 0 4px 12px rgba(8, 145, 178, 0.1);
  transform: translateY(-1px);
  text-decoration: none;
}
.knowledge-card-icon {
  width: 28px;
  height: 28px;
  color: var(--blue);
  margin-bottom: 0.3rem;
}
.knowledge-card-icon svg { width: 100%; height: 100%; }
.knowledge-card h3,
.knowledge-card .knowledge-card-title {
  margin: 0;
  font-size: 15px;
  font-weight: var(--font-weight-bold);
  color: var(--blue);
  line-height: 1.3;
}
.knowledge-card p,
.knowledge-card .knowledge-card-desc {
  margin: 0;
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
}
.knowledge-card-meta {
  font-size: 11px;
  color: var(--text-secondary);
  margin-top: 0.2rem;
}

/* Card grid */
.knowledge-grid {
  display: grid;
  gap: 1rem;
}
@media (min-width: 540px) {
  .knowledge-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 900px) {
  .knowledge-grid { grid-template-columns: repeat(3, 1fr); }
}
.knowledge-grid--2col {
  grid-template-columns: 1fr;
}
@media (min-width: 540px) {
  .knowledge-grid--2col { grid-template-columns: repeat(2, 1fr); }
}

/* ── Callouts ────────────────────────────────────────────────────────────────── */

.knowledge-callout,
.knowledge-warning,
.knowledge-success {
  display: flex;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  border-radius: var(--radius);
  font-size: 14px;
  line-height: 1.6;
  margin: 1.5rem 0;
}
.knowledge-callout {
  background: #f0f9ff;
  border: 1px solid rgba(3,105,161,0.2);
  color: #0c4a6e;
}
.knowledge-warning {
  background: #fef9c3;
  border: 1px solid rgba(202,138,4,0.3);
  color: #713f12;
}
.knowledge-success {
  background: #f0fdf4;
  border: 1px solid rgba(22,101,52,0.2);
  color: #14532d;
}
.knowledge-callout-icon,
.knowledge-warning-icon,
.knowledge-success-icon {
  flex-shrink: 0;
  font-size: 18px;
  line-height: 1.5;
}

/* ── Table ───────────────────────────────────────────────────────────────────── */

.knowledge-table-wrap {
  overflow-x: auto;
  margin: 1.5rem 0;
  border-radius: var(--radius);
  border: 1px solid var(--border-soft);
}
.knowledge-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}
.knowledge-table th {
  text-align: left;
  padding: 0.6rem 0.85rem;
  background: var(--bg-soft);
  font-size: 11px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-soft);
  white-space: nowrap;
}
.knowledge-table td {
  padding: 0.65rem 0.85rem;
  border-bottom: 1px solid var(--border-soft);
  vertical-align: top;
  line-height: 1.5;
}
.knowledge-table tr:last-child td { border-bottom: none; }
.knowledge-table tr:hover td { background: var(--bg-soft); }

/* ── Definition & example ────────────────────────────────────────────────────── */

.knowledge-definition {
  border-left: 3px solid var(--blue);
  padding: 0.75rem 1rem;
  background: var(--blue-light);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 15px;
  line-height: 1.6;
  margin: 1.25rem 0;
}
.knowledge-definition strong {
  display: block;
  font-size: 12px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--blue);
  margin-bottom: 0.4rem;
}
.knowledge-example {
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 1rem 1.25rem;
  font-size: 14px;
  line-height: 1.7;
  margin: 1.25rem 0;
}
.knowledge-example strong {
  display: block;
  font-size: 12px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  margin-bottom: 0.4rem;
}

/* ── Key takeaways ───────────────────────────────────────────────────────────── */

.knowledge-takeaways {
  background: var(--blue-light);
  border: 1px solid rgba(14, 116, 144, 0.2);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
}
.knowledge-takeaways h2 {
  font-size: 14px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--blue);
  margin: 0 0 0.75rem;
}
.knowledge-takeaways ul {
  margin: 0;
  padding: 0 0 0 1.25rem;
}
.knowledge-takeaways li {
  font-size: 14px;
  line-height: 1.7;
  color: var(--text-primary);
  margin-bottom: 0.3rem;
}

/* ── Sources / citations ─────────────────────────────────────────────────────── */

.knowledge-sources {
  font-size: 12px;
  color: var(--text-secondary);
  border-top: 1px solid var(--border-soft);
  padding-top: 1rem;
  margin-top: 2rem;
}
.knowledge-sources ol {
  margin: 0.5rem 0 0;
  padding-left: 1.25rem;
}
.knowledge-sources li {
  margin-bottom: 0.3rem;
  line-height: 1.5;
}

/* ── Knowledge footer ────────────────────────────────────────────────────────── */

.knowledge-footer-links {
  display: grid;
  gap: 1rem;
  margin: 2rem 0 0;
  padding: 2rem 0 0;
  border-top: 1px solid var(--border-soft);
}
@media (min-width: 600px) {
  .knowledge-footer-links {
    grid-template-columns: repeat(2, 1fr);
  }
}
.knowledge-footer-section h4 {
  font-size: 11px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-secondary);
  margin: 0 0 0.5rem;
}
.knowledge-footer-section ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.knowledge-footer-section li {
  font-size: 13px;
  line-height: 1.8;
}
.knowledge-footer-section a {
  color: var(--text-secondary);
  text-decoration: none;
}
.knowledge-footer-section a:hover {
  color: var(--blue);
  text-decoration: underline;
}

/* ── Category hub ────────────────────────────────────────────────────────────── */

.knowledge-hub-hero {
  padding: 2.5rem 0 1.5rem;
  border-bottom: 1px solid var(--border-soft);
  margin-bottom: 2rem;
}
.knowledge-hub-hero h1 {
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1.15;
  margin: 0.5rem 0 0.75rem;
}
.knowledge-hub-hero p {
  font-size: 17px;
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 580px;
  margin: 0;
}
.knowledge-hub-categories {
  display: grid;
  gap: 0.75rem;
}
@media (min-width: 540px) {
  .knowledge-hub-categories { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 900px) {
  .knowledge-hub-categories { grid-template-columns: repeat(4, 1fr); }
}
.knowledge-category-card {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  padding: 1rem 1.1rem;
  background: var(--white);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text-primary);
  transition: border-color 0.15s, transform 0.12s;
}
.knowledge-category-card:hover {
  border-color: var(--blue-soft);
  transform: translateY(-1px);
  text-decoration: none;
}
.knowledge-category-card h3 {
  font-size: 14px;
  font-weight: var(--font-weight-bold);
  margin: 0;
  color: var(--blue);
}
.knowledge-category-card p {
  font-size: 12px;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.5;
}
.knowledge-category-count {
  font-size: 11px;
  color: var(--text-secondary);
  margin-top: 0.25rem;
}

/* ── Formula display ─────────────────────────────────────────────────────────── */

.formula-display {
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-align: center;
  font-size: 20px;
  font-family: var(--font-mono);
  margin: 1.5rem 0;
  overflow-x: auto;
}
.formula-display .formula-equation {
  font-size: clamp(16px, 3vw, 22px);
  color: var(--text-primary);
}
.formula-variable-table {
  margin-top: 1rem;
  font-size: 13px;
  width: 100%;
}
.formula-variable-table td:first-child {
  font-family: var(--font-mono);
  font-weight: var(--font-weight-bold);
  color: var(--blue);
  padding-right: 1rem;
  white-space: nowrap;
  vertical-align: top;
}

/* ── Glossary term ───────────────────────────────────────────────────────────── */

.glossary-term {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--border-soft);
}
.glossary-term:last-child { border-bottom: none; }
.glossary-term-word {
  font-size: 20px;
  font-weight: var(--font-weight-bold);
  color: var(--text-primary);
  margin: 0 0 0.3rem;
}
.glossary-term-phonetic {
  font-size: 13px;
  color: var(--text-secondary);
  font-style: italic;
  margin-bottom: 0.5rem;
}
.glossary-term-definition {
  font-size: 15px;
  line-height: 1.6;
  color: var(--text-primary);
}

/* ── Search page ─────────────────────────────────────────────────────────────── */

.search-form {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}
.search-input {
  flex: 1;
  padding: 0.7rem 1rem;
  font-size: 16px;
  border: 1.5px solid var(--border-soft);
  border-radius: var(--radius);
  outline: none;
  transition: border-color 0.15s;
  background: var(--white);
  color: var(--text-primary);
}
.search-input:focus {
  border-color: var(--blue);
}
.search-result-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border-soft);
}
.search-result-item:last-child { border-bottom: none; }
.search-result-category {
  font-size: 11px;
  font-weight: var(--font-weight-bold);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--blue);
  margin-bottom: 0.2rem;
}
.search-result-title {
  font-size: 16px;
  font-weight: var(--font-weight-bold);
  color: var(--text-primary);
  text-decoration: none;
}
.search-result-title:hover { color: var(--blue); }
.search-result-desc {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-top: 0.25rem;
}
.search-empty {
  text-align: center;
  padding: 3rem 0;
  color: var(--text-secondary);
  font-size: 15px;
}

/* ── Nav search icon ─────────────────────────────────────────────────────────── */

.nav-end {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-left: auto;
}
.nav-search {
  display: inline-flex;
  align-items: center;
  padding: 0.3rem;
  color: var(--text-secondary);
  text-decoration: none;
  border-radius: 6px;
  transition: color 0.15s, background 0.15s;
}
.nav-search:hover {
  color: var(--blue);
  background: var(--bg-soft);
}
.nav-search svg {
  width: 18px;
  height: 18px;
}