* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #f4f6fb;
  color: #111827;
}

.app-shell {
  display: flex;
  min-height: 100vh;
}

/* Sidebar */

.sidebar {
  width: 340px;
  background: radial-gradient(circle at top left, #1f3a8a 0, #020617 55%);
  color: #e5e7eb;
  padding: 20px 18px 24px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  position: sticky;
  top: 0;
  max-height: 100vh;
  overflow-y: auto;
}

.logo-block {
  display: flex;
  gap: 12px;
  align-items: center;
  margin-bottom: 8px;
}

.logo-mark {
  width: 52px;
  height: 52px;
  border-radius: 16px;
  border: 2px solid rgba(251,191,36,0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  letter-spacing: 0.08em;
  font-size: 18px;
  color: #facc15;
  background: radial-gradient(circle at 30% 20%, rgba(250,250,250,0.15), transparent 50%);
}

.logo-text {
  display: flex;
  flex-direction: column;
}

.logo-title {
  font-size: 15px;
  font-weight: 600;
  line-height: 1.3;
}

.logo-sub {
  font-size: 11px;
  color: #9ca3af;
}

.search-box {
  margin-top: 4px;
}

.search-box input {
  width: 100%;
  padding: 8px 10px;
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.8);
  background: rgba(15,23,42,0.7);
  color: #e5e7eb;
  font-size: 13px;
}

.search-box input::placeholder {
  color: #9ca3af;
}

.nav-container {
  margin-top: 10px;
  padding-right: 4px;
}

.part-item {
  margin-bottom: 6px;
  border-radius: 10px;
  overflow: hidden;
  background: rgba(15,23,42,0.8);
  border: 1px solid transparent;
}

.part-header {
  padding: 8px 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
}

.part-header-title {
  font-size: 13px;
  font-weight: 600;
  color: #e5e7eb;
}

.part-header span.part-label {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: #9ca3af;
}

.part-toggle {
  font-size: 14px;
  color: #9ca3af;
}

.part-item.open {
  border-color: rgba(250,204,21,0.8);
  background: radial-gradient(circle at top left, rgba(56,189,248,0.2), rgba(15,23,42,0.95));
}

.section-list {
  display: none;
  padding: 4px 0 6px;
  border-top: 1px solid rgba(31,41,55,0.9);
}

.part-item.open .section-list {
  display: block;
}

.section-link {
  padding: 6px 12px 6px 16px;
  font-size: 12px;
  cursor: pointer;
  color: #d1d5db;
  border-left: 2px solid transparent;
}

.section-link:hover {
  background: rgba(15,23,42,0.9);
  border-left-color: #facc15;
}

.section-link.active {
  background: rgba(15,23,42,1);
  border-left-color: #facc15;
  color: #fefce8;
}

/* Main content */

.content {
  flex: 1;
  padding: 28px 36px 40px;
}

.content-header {
  margin-bottom: 18px;
  border-bottom: 1px solid #e5e7eb;
  padding-bottom: 10px;
}

#contentTitle {
  margin: 0 0 4px;
  font-size: 26px;
  color: #0f172a;
}

#contentTagline {
  margin: 0;
  font-size: 14px;
  color: #6b7280;
}

.content-body {
  background: #ffffff;
  border-radius: 18px;
  padding: 20px 22px;
  box-shadow: 0 18px 45px rgba(15,23,42,0.08);
}

.content-body h2 {
  margin-top: 0;
  color: #111827;
}

.content-body p {
  font-size: 15px;
  line-height: 1.6;
  color: #374151;
}

.content-body h3 {
  margin-top: 18px;
  margin-bottom: 6px;
  font-size: 16px;
}

.section-meta {
  font-size: 12px;
  color: #6b7280;
  margin-bottom: 6px;
}

.badge {
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  padding: 3px 9px;
  font-size: 11px;
  margin-right: 6px;
}

.badge-part {
  background: rgba(37,99,235,0.08);
  color: #1d4ed8;
}

.badge-status {
  background: rgba(22,163,74,0.08);
  color: #15803d;
}

.button-row {
  margin-top: 14px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.btn {
  border-radius: 999px;
  padding: 7px 14px;
  font-size: 13px;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: linear-gradient(135deg, #facc15, #f97316);
  color: #111827;
  font-weight: 600;
}

.btn-outline {
  background: transparent;
  border: 1px solid #e5e7eb;
  color: #374151;
}

/* Responsive */

@media (max-width: 900px) {
  .sidebar {
    position: fixed;
    width: 260px;
    transform: translateX(-100%);
    transition: transform 0.25s ease-out;
    z-index: 50;
  }
  .sidebar.open {
    transform: translateX(0);
  }
  .content {
    margin-left: 0;
    padding: 18px 16px 28px;
  }
}