/* Mobile-first, modern, clean styling */
:root {
  --bg: #0b1020;
  --bg-alt: #111728;
  --card: #151b2e;
  --accent: #ffd166;
  --accent-soft: rgba(255, 209, 102, 0.12);
  --text: #f5f7ff;
  --muted: #a4acc4;
  --danger: #ff6b6b;
  --radius-lg: 16px;
  --radius-md: 10px;
  --shadow-soft: 0 18px 45px rgba(0, 0, 0, 0.35);
  --shadow-subtle: 0 10px 26px rgba(0, 0, 0, 0.3);
  --nav-height: 64px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", sans-serif;
  background: radial-gradient(circle at top, #1c2541 0, #050816 55%, #020617 100%);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

a:hover {
  text-decoration: underline;
}

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

.app-main {
  flex: 1;
  padding: 1.1rem 1rem 4rem;
  max-width: 1080px;
  width: 100%;
  margin: 0 auto;
}

/* Top nav */
.top-nav {
  position: sticky;
  top: 0;
  z-index: 40;
  backdrop-filter: blur(18px);
  background: radial-gradient(circle at top, rgba(15,23,42,0.96), rgba(2,6,23,0.94));
  border-bottom: 1px solid rgba(148, 163, 184, 0.25);
}

.top-nav-inner {
  max-width: 1080px;
  margin: 0 auto;
  padding: 0.35rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.55rem;
}

.brand-icon {
  width: 28px;
  height: 28px;
  border-radius: 999px;
  background: radial-gradient(circle at 20% 0%, #fbbf24, #f97316 38%, #ec4899 70%, #4f46e5 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 0 1px rgba(15,23,42,0.7), 0 10px 22px rgba(0,0,0,0.5);
  font-size: 0.85rem;
  font-weight: 700;
  color: #0b1020;
}

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

.brand-text-primary {
  font-size: 0.95rem;
  font-weight: 650;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.brand-text-sub {
  font-size: 0.72rem;
  color: var(--muted);
}

.nav-links {
  display: none;
  gap: 0.75rem;
  align-items: center;
  font-size: 0.82rem;
}

.nav-link-pill {
  padding: 0.35rem 0.65rem;
  border-radius: 999px;
  border: 1px solid transparent;
  background: transparent;
  color: var(--muted);
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.nav-link-pill span {
  font-size: 0.78rem;
}

.nav-link-pill.active {
  background: rgba(15,23,42,0.9);
  border-color: rgba(148,163,184,0.38);
  color: var(--accent);
}

.nav-link-pill-dot {
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: var(--accent);
}

@media (min-width: 768px) {
  .nav-links {
    display: flex;
  }
}

/* Hero + cards */
.hero {
  margin-top: 1.1rem;
  margin-bottom: 1.1rem;
}

.hero-kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.18rem 0.6rem;
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.4);
  background: radial-gradient(circle at left, rgba(56,189,248,0.18), transparent);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.hero-kicker-dot {
  width: 7px;
  height: 7px;
  border-radius: 999px;
  background: #22c55e;
  box-shadow: 0 0 0 5px rgba(34,197,94,0.18);
}

.hero-title {
  font-size: 1.6rem;
  line-height: 1.15;
  margin: 0.6rem 0 0.3rem;
}

.hero-highlight {
  background: linear-gradient(120deg, #fbbf24, #22c55e 35%, #38bdf8 70%, #818cf8 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-subtitle {
  font-size: 0.92rem;
  color: var(--muted);
  max-width: 36rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 0.8rem;
}

.btn {
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.5);
  padding: 0.55rem 0.85rem;
  font-size: 0.85rem;
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: rgba(15,23,42,0.9);
  color: var(--text);
  cursor: pointer;
}

.btn-primary {
  background: linear-gradient(135deg, #fbbf24, #f97316);
  color: #111827;
  border-color: rgba(148,163,184,0.25);
}

.btn-soft {
  background: rgba(15,23,42,0.8);
}

/* Layout grid */
.grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1rem;
}

@media (min-width: 900px) {
  .grid-2 {
    grid-template-columns: minmax(0, 2fr) minmax(0, 1.4fr);
    align-items: flex-start;
  }
}

/* Cards */
.card {
  background: radial-gradient(circle at top left, rgba(148,163,184,0.2), transparent 60%),
              radial-gradient(circle at bottom right, rgba(15,23,42,0.95), #020617);
  border-radius: var(--radius-lg);
  padding: 0.9rem 0.9rem 1.05rem;
  box-shadow: var(--shadow-soft);
  border: 1px solid rgba(148,163,184,0.4);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.25rem;
  margin-bottom: 0.55rem;
}

.card-title {
  font-size: 0.9rem;
  font-weight: 600;
}

.card-pill {
  font-size: 0.7rem;
  padding: 0.18rem 0.5rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
}

.card-body {
  font-size: 0.8rem;
  color: var(--muted);
}

/* Search + table */
.search-row {
  display: flex;
  flex-direction: column;
  gap: 0.45rem;
  margin-bottom: 0.75rem;
}

.search-input-wrap {
  position: relative;
}

.search-input {
  width: 100%;
  padding: 0.55rem 0.75rem 0.55rem 1.95rem;
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.5);
  background: rgba(15,23,42,0.9);
  color: var(--text);
  font-size: 0.82rem;
}

.search-input::placeholder {
  color: rgba(148,163,184,0.8);
}

.search-icon {
  position: absolute;
  left: 0.7rem;
  top: 50%;
  transform: translateY(-50%);
  font-size: 0.9rem;
  color: var(--muted);
}

/* Tiny pill filters */
.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.chip {
  font-size: 0.7rem;
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.5);
  background: rgba(15,23,42,0.9);
  color: var(--muted);
  cursor: pointer;
}

.chip.active {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: rgba(250, 204, 21, 0.8);
}

/* Topic table */
.table-wrap {
  border-radius: var(--radius-lg);
  border: 1px solid rgba(148,163,184,0.4);
  background: rgba(15,23,42,0.96);
  overflow: hidden;
  box-shadow: var(--shadow-subtle);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.78rem;
}

.table thead {
  background: radial-gradient(circle at top, rgba(15,23,42,0.9), #020617);
}

.table th,
.table td {
  padding: 0.5rem 0.6rem;
  text-align: left;
}

.table th {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--muted);
  letter-spacing: 0.06em;
  cursor: pointer;
  white-space: nowrap;
}

.table th.sortable:hover {
  color: var(--accent);
}

.table tbody tr:nth-child(odd) {
  background: rgba(15,23,42,0.9);
}

.table tbody tr:nth-child(even) {
  background: rgba(15,23,42,0.96);
}

.table tbody tr:hover {
  background: rgba(30,64,175,0.7);
}

.badge {
  font-size: 0.7rem;
  padding: 0.12rem 0.45rem;
  border-radius: 999px;
  border: 1px solid rgba(148,163,184,0.5);
  color: var(--muted);
}

.badge-foundation {
  border-color: rgba(56,189,248,0.7);
  color: #7dd3fc;
}

.badge-principle {
  border-color: rgba(129,140,248,0.7);
  color: #a5b4fc;
}

.badge-strategy {
  border-color: rgba(52,211,153,0.7);
  color: #6ee7b7;
}

.badge-case {
  border-color: rgba(248,250,252,0.7);
  color: #e5e7eb;
}

/* Content page layout */
.page-header {
  margin-bottom: 0.8rem;
}

.breadcrumbs {
  font-size: 0.74rem;
  color: var(--muted);
  margin-bottom: 0.35rem;
}

.page-title {
  margin: 0.1rem 0 0.4rem;
  font-size: 1.25rem;
}

.page-meta {
  font-size: 0.78rem;
  color: var(--muted);
}

.section {
  margin-bottom: 1rem;
}

.section-title {
  font-size: 0.9rem;
  margin-bottom: 0.35rem;
}

.section p {
  font-size: 0.82rem;
  color: var(--muted);
}

ul.feature-list {
  padding-left: 1.1rem;
  margin: 0.1rem 0 0.3rem;
}

ul.feature-list li {
  margin-bottom: 0.22rem;
}

/* Video grid */
.video-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0.6rem;
}

@media (min-width: 640px) {
  .video-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.video-card {
  border-radius: var(--radius-md);
  padding: 0.6rem 0.65rem;
  background: linear-gradient(140deg, rgba(15,23,42,0.96), rgba(30,64,175,0.95));
  border: 1px solid rgba(148,163,184,0.55);
}

.video-title {
  font-size: 0.82rem;
  margin-bottom: 0.15rem;
}

.video-meta {
  font-size: 0.72rem;
  color: var(--muted);
  margin-bottom: 0.25rem;
}

/* Footer */
.app-footer {
  border-top: 1px solid rgba(148,163,184,0.25);
  padding: 0.75rem 1rem 1.5rem;
  font-size: 0.72rem;
  color: var(--muted);
  text-align: center;
  background: rgba(3,7,18,0.96);
}

/* Utility */
.text-accent {
  color: var(--accent);
}

.text-muted {
  color: var(--muted);
}