:root {
  --bg: #0b0e1a;
  --bg-panel: #131729;
  --bg-card: #171c33;
  --bg-card-hover: #1d2340;
  --border: #262c4a;
  --text: #eef0fb;
  --text-dim: #9aa1c4;
  --text-faint: #666d94;
  --accent: #5b8cff;
  --accent-2: #ffcf5b;
  --good: #4ade80;
  --radius: 16px;
  --radius-sm: 10px;
  font-size: 16px;
}

:root[data-theme="light"] {
  --bg: #f4f5fb;
  --bg-panel: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #eef0fc;
  --border: #dde0f2;
  --text: #1a1d2e;
  --text-dim: #565d7e;
  --text-faint: #8a8fb0;
}

@media (prefers-color-scheme: light) {
  :root:not([data-theme="dark"]) {
    --bg: #f4f5fb;
    --bg-panel: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #eef0fc;
    --border: #dde0f2;
    --text: #1a1d2e;
    --text-dim: #565d7e;
    --text-faint: #8a8fb0;
  }
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, sans-serif;
}

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

.hub-shell {
  max-width: 1040px;
  width: 100%;
  margin: 0 auto;
  padding: 40px 20px 60px;
  display: flex;
  flex-direction: column;
  gap: 32px;
  flex: 1;
}

.hub-header {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 10px;
  padding: 20px 0 8px;
}
.hub-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 800;
  font-size: 2rem;
  letter-spacing: -0.02em;
}
.hub-brand .spark { font-size: 2.2rem; }
.hub-tagline {
  color: var(--text-dim);
  font-size: 1.05rem;
  max-width: 520px;
  line-height: 1.5;
}

.hub-section-label {
  font-size: 0.75rem;
  font-weight: 800;
  color: var(--text-faint);
  text-transform: uppercase;
  letter-spacing: .06em;
  padding-left: 2px;
}

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

.course-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  text-decoration: none;
  color: var(--text);
  position: relative;
  overflow: hidden;
  transition: transform .14s ease, border-color .14s ease, background .14s ease;
}
.course-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 4px;
  background: var(--card-accent, var(--accent));
}
.course-card:hover {
  transform: translateY(-3px);
  border-color: var(--card-accent, var(--accent));
  background: var(--bg-card-hover);
}
.course-card.disabled {
  opacity: 0.55;
  cursor: default;
  pointer-events: none;
}

.cc-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
}
.cc-icon { font-size: 2rem; line-height: 1; }
.cc-status {
  font-size: 0.65rem;
  font-weight: 800;
  color: var(--text-faint);
  letter-spacing: .06em;
  text-transform: uppercase;
  background: var(--bg);
  padding: 4px 9px;
  border-radius: 999px;
  white-space: nowrap;
}
.cc-status.live { color: var(--good); }

.course-card h3 {
  margin: 0;
  font-size: 1.15rem;
  letter-spacing: -0.01em;
}
.course-card p {
  margin: 0;
  font-size: 0.86rem;
  color: var(--text-dim);
  line-height: 1.5;
}
.cc-meta {
  margin-top: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.72rem;
  color: var(--text-faint);
  padding-top: 6px;
  border-top: 1px solid var(--border);
}
.cc-go {
  font-weight: 800;
  color: var(--card-accent, var(--accent));
}

.hub-footer {
  text-align: center;
  color: var(--text-faint);
  font-size: 0.78rem;
  padding-top: 20px;
}
.hub-footer a { color: var(--text-dim); }

@media (max-width: 560px) {
  .hub-brand { font-size: 1.5rem; }
  .hub-brand .spark { font-size: 1.7rem; }
}