/* ═══════════════════════════════════════════
   KNOWLEDGE HUB PAGE CSS
   ═══════════════════════════════════════════ */

/* ── PAGE HEADER ── */
.kh-page-header {
  padding: 100px 0 40px;
  background: var(--bg-2);
  border-bottom: 1px solid var(--border);
}

.kh-back {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 13px;
  color: var(--text-3);
  margin-bottom: 20px;
  transition: var(--trans);
}
.kh-back:hover { color: var(--purple-lt); }

.kh-title {
  font-family: var(--font-head);
  font-size: clamp(36px, 4vw, 58px);
  font-weight: 700;
  letter-spacing: -1px;
  line-height: 1.1;
  margin-bottom: 12px;
}
.kh-title em { font-style: italic; color: var(--purple-lt); }
.kh-subtitle { font-size: 16px; color: var(--text-2); max-width: 540px; margin-bottom: 32px; }

/* CONTROLS */
.kh-controls { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; margin-bottom: 20px; }

.kh-search-wrap {
  display: flex; align-items: center; gap: 10px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 10px; padding: 10px 16px;
  flex: 1; max-width: 360px; transition: var(--trans);
}
.kh-search-wrap:focus-within { border-color: var(--border-p); }
.kh-search-icon { font-size: 14px; flex-shrink: 0; }
.kh-search {
  flex: 1; background: none; border: none; outline: none;
  color: var(--text); font-size: 14px; font-family: var(--font-body);
}
.kh-search::placeholder { color: var(--text-3); }

.kh-filters { display: flex; gap: 8px; flex-wrap: wrap; }
.kh-filter {
  padding: 8px 16px; border-radius: 100px;
  font-size: 13px; font-weight: 500;
  border: 1px solid var(--border); color: var(--text-2);
  background: none; cursor: pointer; transition: var(--trans);
  font-family: var(--font-body);
}
.kh-filter:hover { border-color: var(--border-p); color: var(--text); }
.kh-filter.active { background: var(--purple); border-color: var(--purple); color: #fff; }

.kh-stats-bar {
  font-size: 13px; color: var(--text-3);
  padding: 10px 0;
  border-top: 1px solid var(--border);
}

/* ── BODY LAYOUT ── */
.kh-body {
  background: var(--bg); min-height: 60vh;
  padding: 48px 0 80px;
}
.kh-body .container {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 48px;
  align-items: start;
}

/* ── SIDEBAR TOC ── */
.kh-sidebar {
  position: sticky; top: 88px;
}
.kh-sidebar-title {
  font-size: 11px; font-weight: 700; letter-spacing: 2px;
  text-transform: uppercase; color: var(--text-3);
  margin-bottom: 12px; padding: 0 4px;
}
.kh-toc { display: flex; flex-direction: column; gap: 2px; }
.kh-toc-item {
  display: block; padding: 8px 12px;
  font-size: 13px; font-weight: 500; color: var(--text-2);
  border-radius: 8px; transition: var(--trans);
  border-left: 2px solid transparent;
}
.kh-toc-item:hover { color: var(--text); background: var(--bg-card); }
.kh-toc-item.active { color: var(--purple-lt); border-left-color: var(--purple); background: var(--purple-bg); }

/* ── LOADING ── */
.kh-loading {
  display: flex; flex-direction: column; align-items: center;
  gap: 16px; padding: 80px 0; color: var(--text-3);
}
.kh-spinner {
  width: 32px; height: 32px;
  border: 2px solid var(--border);
  border-top-color: var(--purple);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── EMPTY STATE ── */
.kh-empty {
  flex-direction: column; align-items: center;
  gap: 12px; padding: 80px 20px;
  text-align: center; color: var(--text-3);
}
.kh-empty span { font-size: 48px; display: block; }
.kh-empty h3 { font-size: 20px; color: var(--text-2); }
.kh-empty p  { font-size: 14px; }
.kh-empty a  { color: var(--purple-lt); }

/* ── CATEGORY GROUP ── */
.kh-group { margin-bottom: 48px; }

.kh-group-header {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 16px; padding-bottom: 12px;
  border-bottom: 2px solid var(--border);
}
.kh-group-label {
  font-family: var(--font-head);
  font-size: 20px; font-weight: 700; color: var(--text);
}
.kh-group-count {
  font-size: 12px; color: var(--text-3);
  background: var(--bg-card); border: 1px solid var(--border);
  padding: 3px 10px; border-radius: 100px;
}

/* ── NOTE CARD ── */
.kh-note-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 14px;
  margin-bottom: 12px;
  overflow: hidden;
  transition: border-color 0.22s, box-shadow 0.22s;
}
.kh-note-card:hover { border-color: var(--border-p); }
.kh-note-card.open  { border-color: var(--border-p); box-shadow: 0 8px 32px rgba(139,92,246,0.12); }

/* CARD HEAD — clickable */
.kh-note-head {
  display: flex; align-items: center; justify-content: space-between;
  padding: 22px 24px; cursor: pointer; user-select: none;
  transition: background 0.18s;
}
.kh-note-head:hover { background: var(--bg-card-h); }

.kh-note-identity { display: flex; align-items: center; gap: 16px; flex: 1; min-width: 0; }
.kh-note-icon { font-size: 28px; flex-shrink: 0; }
.kh-note-meta { min-width: 0; }
.kh-note-title { font-size: 18px; font-weight: 700; color: var(--text); line-height: 1.3; }
.kh-note-desc  { font-size: 13px; color: var(--text-2); margin-top: 2px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

.kh-note-right {
  display: flex; align-items: center; gap: 14px;
  flex-shrink: 0; margin-left: 20px;
}

.kh-skill-wrap { display: flex; align-items: center; gap: 8px; }
.kh-skill-track {
  width: 80px; height: 4px;
  background: var(--border); border-radius: 100px; overflow: hidden;
}
.kh-skill-fill {
  height: 100%; width: 0; border-radius: 100px;
  background: linear-gradient(90deg, var(--purple-dk), var(--purple-lt));
  transition: width 1s ease;
}
.kh-skill-label { font-size: 12px; font-weight: 700; color: var(--purple-lt); width: 32px; }

.kh-cat-badge {
  font-size: 10px; font-weight: 700; letter-spacing: 0.5px;
  padding: 4px 10px; border-radius: 100px;
  background: var(--purple-bg); border: 1px solid var(--border-p);
  color: var(--purple-lt); text-transform: uppercase;
  white-space: nowrap;
}

.kh-toggle-icon {
  font-size: 18px; color: var(--text-3); transition: transform 0.22s;
  width: 20px; text-align: center; flex-shrink: 0;
}
.kh-note-card.open .kh-toggle-icon { transform: rotate(90deg); color: var(--purple-lt); }

/* CARD BODY — expandable */
.kh-note-body {
  display: none;
  padding: 0 24px 28px;
  border-top: 1px solid var(--border);
  animation: slideDown 0.22s ease;
}
.kh-note-card.open .kh-note-body { display: flex; flex-direction: column; gap: 28px; }

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* SECTIONS inside card */
.kh-section { display: flex; flex-direction: column; gap: 12px; padding-top: 20px; }

.kh-section-label {
  font-size: 11px; font-weight: 700; letter-spacing: 1.5px;
  text-transform: uppercase; color: var(--text-3);
}

.kh-notes-text {
  font-size: 15px; color: var(--text-2); line-height: 1.8;
  padding: 16px 20px;
  background: rgba(139,92,246,0.04);
  border-left: 3px solid var(--purple);
  border-radius: 0 8px 8px 0;
}

/* CONCEPTS GRID */
.kh-concepts-grid { display: flex; flex-direction: column; gap: 10px; }

.kh-concept {
  display: flex; align-items: flex-start; gap: 14px;
  padding: 14px 16px;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: 10px;
  transition: var(--trans);
}
.kh-concept:hover { border-color: var(--border-p); background: var(--bg-card-h); }

.kh-concept-num {
  font-size: 11px; font-weight: 700;
  color: var(--purple-lt); background: var(--purple-bg);
  border: 1px solid var(--border-p);
  padding: 2px 7px; border-radius: 5px;
  flex-shrink: 0; font-family: monospace; margin-top: 1px;
}

.kh-concept-body { font-size: 14px; color: var(--text-2); line-height: 1.6; }
.kh-concept-body strong { color: var(--text); font-weight: 600; }
.kh-concept-sep { margin: 0 5px; color: var(--text-3); }

/* PROJECT CHIP */
.kh-project-chip {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 10px 18px;
  background: var(--bg-2); border: 1px solid var(--border-p);
  border-radius: 10px; color: var(--purple-lt);
  font-size: 14px; font-weight: 600;
  transition: var(--trans);
}
.kh-project-chip:hover { background: var(--purple-bg); }
.kh-project-icon { font-size: 16px; }

/* ── RESPONSIVE ── */
@media (max-width: 900px) {
  .kh-body .container { grid-template-columns: 1fr; }
  .kh-sidebar { display: none; }
}
@media (max-width: 600px) {
  .kh-controls { flex-direction: column; align-items: stretch; }
  .kh-search-wrap { max-width: 100%; }
  .kh-note-right { display: none; }
  .kh-note-head { padding: 16px; }
  .kh-note-body { padding: 0 16px 20px; }
}