/* Hub compartido — Matemáticas, Física y secciones similares */

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

body.section-hub {
  margin: 0;
  min-height: 100vh;
  background: var(--section-bg);
  background-image:
    radial-gradient(at 15% 20%, var(--hero-glow-1) 0px, transparent 45%),
    radial-gradient(at 85% 75%, var(--hero-glow-2) 0px, transparent 45%);
  background-attachment: fixed;
  color: var(--section-text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
}

.hub-main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 48px 24px 80px;
}

.hub-section {
  margin-bottom: 48px;
}

.hub-section-head {
  margin-bottom: 28px;
  text-align: center;
}

.hub-section-title {
  margin: 0 0 8px;
  font-size: clamp(1.25rem, 2.5vw, 1.5rem);
  font-weight: 800;
  color: #fff;
  letter-spacing: -0.02em;
}

.hub-section-title::after {
  content: '';
  display: block;
  width: 48px;
  height: 4px;
  margin: 12px auto 0;
  background: linear-gradient(90deg, var(--hero-primary), var(--hero-accent));
  border-radius: 2px;
}

.hub-section-desc {
  margin: 0 auto;
  max-width: 560px;
  font-size: 14px;
  color: var(--section-muted);
  line-height: 1.55;
}

.hub-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}

.hub-card {
  display: flex;
  flex-direction: column;
  padding: 24px;
  border-radius: 16px;
  background: linear-gradient(145deg, rgba(30, 32, 36, 0.95), rgba(35, 39, 43, 0.95));
  border: 1px solid var(--section-border);
  text-decoration: none;
  color: inherit;
  transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
}

.hub-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.25);
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.35);
}

.theme-math .hub-card:hover { border-color: rgba(129, 140, 248, 0.5); }
.theme-physics .hub-card:hover { border-color: rgba(245, 158, 11, 0.5); }

.hub-card--soon {
  opacity: 0.65;
  cursor: default;
  pointer-events: none;
}

.hub-card__icon {
  font-size: 2rem;
  margin-bottom: 12px;
  line-height: 1;
}

.hub-card__tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: rgba(255, 255, 255, 0.08);
  color: var(--hero-primary);
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.hub-card__tag--muted {
  background: rgba(255, 255, 255, 0.06);
  color: var(--section-muted);
  border-color: var(--section-border);
}

.hub-card h3 {
  margin: 0 0 8px;
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff;
}

.hub-card p {
  margin: 0;
  font-size: 14px;
  color: var(--section-muted);
  line-height: 1.5;
  flex: 1;
}

.hub-card__link {
  margin-top: 16px;
  font-size: 13px;
  font-weight: 700;
  color: var(--hero-accent);
}

.hub-notice {
  padding: 28px;
  border-radius: 16px;
  text-align: center;
  background: linear-gradient(145deg, rgba(30, 32, 36, 0.95), rgba(35, 39, 43, 0.95));
  border: 1px dashed var(--section-border);
}

.hub-notice p {
  margin: 0;
  color: var(--section-muted);
  font-size: 15px;
}