/* ---------- Breadcrumb ---------- */
.brand-link {
  display: inline-flex; align-items: center; gap: 10px;
  text-decoration: none; color: inherit;
  opacity: 0.85; transition: opacity 0.2s;
}
.brand-link:hover { opacity: 1; }
.crumb-sep { margin: 0 10px; color: var(--text-faint); }
.crumb-current { font-weight: 600; }

/* ---------- Docs hero ---------- */
.docs-hero h1 { font-size: clamp(24px, 3vw, 32px); }

/* ---------- Collections ---------- */
.collections { margin-bottom: 28px; }
.collections-head,
.docs-section-head {
  font-size: 13px;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 12px;
}
.docs-section-head { margin-top: 4px; }
.collection-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 14px;
}
.collection-card {
  display: flex; align-items: center; gap: 16px;
  padding: 18px 20px;
  border-radius: var(--radius-lg);
  text-decoration: none; color: inherit;
  background: linear-gradient(135deg, rgba(130,230,180,0.16), rgba(255,255,255,0.06));
  border: 1px solid rgba(130,230,180,0.28);
  backdrop-filter: blur(24px) saturate(160%);
  -webkit-backdrop-filter: blur(24px) saturate(160%);
  box-shadow: var(--glass-shadow);
  transition: transform 0.25s, border-color 0.25s, background 0.25s;
}
.collection-card:hover {
  transform: translateY(-3px);
  border-color: rgba(130,230,180,0.5);
}
.col-icon {
  width: 52px; height: 52px; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 28px;
  border-radius: 14px;
  background: rgba(130,230,180,0.18);
  border: 1px solid rgba(130,230,180,0.3);
}
.col-body { display: flex; flex-direction: column; gap: 3px; min-width: 0; }
.col-title { font-size: 17px; font-weight: 700; }
.col-arrow { color: rgba(130,230,180,0.9); margin-left: 2px; }
.col-desc { font-size: 13px; color: var(--text-dim); }
.col-meta { font-size: 11px; color: var(--text-faint); margin-top: 3px; font-variant-numeric: tabular-nums; }

/* ---------- Filter chips ---------- */
.filter-bar {
  display: flex; gap: 8px; flex-wrap: wrap;
  padding: 10px 12px;
  border-radius: 999px;
  margin-bottom: 24px;
}
.chip {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid transparent;
  color: var(--text-dim);
  cursor: pointer;
  font-size: 13px;
  font-family: inherit;
  transition: all 0.2s;
}
.chip:hover { background: rgba(255, 255, 255, 0.12); color: var(--text); }
.chip.active {
  background: rgba(255, 255, 255, 0.18);
  border-color: rgba(255, 255, 255, 0.32);
  color: var(--text);
}
.chip-count {
  font-size: 11px;
  opacity: 0.6;
  font-variant-numeric: tabular-nums;
}

/* ---------- Doc grid ---------- */
.doc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}

.doc-card {
  display: flex; flex-direction: column;
  padding: 20px;
  border-radius: var(--radius-lg);
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  backdrop-filter: blur(24px) saturate(160%);
  -webkit-backdrop-filter: blur(24px) saturate(160%);
  box-shadow: var(--glass-shadow);
  text-decoration: none;
  color: inherit;
  transition: transform 0.25s, background 0.25s, border-color 0.25s;
  min-height: 180px;
  position: relative;
}
.doc-card:hover {
  transform: translateY(-3px);
  background: var(--glass-bg-hover);
  border-color: rgba(255, 255, 255, 0.32);
}

.doc-card-head {
  display: flex; align-items: center; justify-content: space-between;
  margin-bottom: 14px;
}
.doc-cat {
  font-size: 11px;
  text-transform: uppercase; letter-spacing: 0.5px;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.08);
  color: var(--text-dim);
}
.doc-date { font-size: 12px; color: var(--text-faint); font-variant-numeric: tabular-nums; }

.doc-card h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 6px;
  line-height: 1.35;
  letter-spacing: -0.2px;
}
.doc-card .doc-desc {
  font-size: 13px;
  color: var(--text-dim);
  line-height: 1.5;
  flex: 1;
  margin-bottom: 14px;
}
.doc-tags {
  display: flex; flex-wrap: wrap; gap: 6px;
}
.doc-tag {
  font-size: 11px;
  padding: 3px 8px;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-faint);
}

/* ---------- 학습 단계 뱃지 (기본/심화) ---------- */
.doc-level {
  font-size: 10.5px;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 999px;
  letter-spacing: 0.02em;
  margin-left: 6px;
  white-space: nowrap;
}
.doc-level.lv-basic {
  background: rgba(56, 189, 248, 0.18);
  color: #38bdf8;
  border: 1px solid rgba(56, 189, 248, 0.4);
}
.doc-level.lv-advanced {
  background: rgba(251, 146, 60, 0.18);
  color: #fb923c;
  border: 1px solid rgba(251, 146, 60, 0.4);
}

/* ---------- 카테고리별 그룹 섹션 ('전체' 필터 시) ---------- */
.doc-grid.grouped {
  display: block;
}
.cat-group {
  margin-bottom: 28px;
}
.cat-group:last-child {
  margin-bottom: 0;
}
.cat-group-head {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  margin: 0 0 12px;
  padding-left: 4px;
}
.cat-group-head .cat-icon { font-size: 18px; }
.cat-group-head .cat-count {
  font-size: 12px;
  opacity: 0.5;
  font-variant-numeric: tabular-nums;
  margin-left: 2px;
}
.doc-grid-inner {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 16px;
}

/* ---------- Empty state ---------- */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-faint);
}
.empty-icon { font-size: 48px; margin-bottom: 12px; opacity: 0.5; }
.hidden { display: none; }