/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  position: relative;
  background: linear-gradient(180deg, var(--color-primary-dark) 0%, #2a1638 100%);
  color: rgba(255, 255, 255, 0.8);
  padding-top: var(--space-2xl);
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary-light), var(--color-accent) 50%, var(--color-primary-light));
}

.site-footer a {
  color: rgba(255, 255, 255, 0.8);
  transition: color var(--transition-fast);
}

.site-footer a:hover {
  color: var(--color-accent);
}

.site-footer__grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr 1fr 1.2fr;
  gap: var(--space-lg);
  padding-bottom: var(--space-xl);
  border-bottom: 1px solid rgba(255, 255, 255, 0.12);
}

.site-footer__brand img {
  height: 48px;
  margin-bottom: var(--space-sm);
  filter: brightness(0) invert(1);
}

.site-footer__brand p {
  color: rgba(255, 255, 255, 0.65);
  font-size: var(--fs-sm);
  max-width: 32ch;
}

.site-footer__social {
  display: flex;
  gap: var(--space-xs);
  margin-top: var(--space-md);
}

.site-footer__social a {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: var(--radius-full);
  background: rgba(255, 255, 255, 0.08);
  transition: background var(--transition-fast), color var(--transition-fast), transform var(--transition-fast);
}

.site-footer__social a:hover {
  background: var(--color-accent);
  color: var(--color-primary-dark);
  transform: translateY(-3px);
}

.site-footer__col h4 {
  position: relative;
  display: inline-block;
  color: var(--color-white);
  font-size: var(--fs-sm);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: var(--space-md);
}

.site-footer__col h4::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -8px;
  width: 24px;
  height: 2px;
  background: var(--color-accent);
}

.site-footer__col ul {
  display: flex;
  flex-direction: column;
  gap: var(--space-xs);
  font-size: var(--fs-sm);
}

.site-footer__col ul a {
  display: inline-flex;
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.site-footer__col ul a:hover {
  transform: translateX(4px);
}

.site-footer__contact li {
  display: flex;
  gap: var(--space-2xs);
  font-size: var(--fs-sm);
  margin-bottom: var(--space-xs);
  color: rgba(255, 255, 255, 0.8);
}

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: var(--space-xs);
  padding-block: var(--space-md);
  font-size: var(--fs-xs);
  color: rgba(255, 255, 255, 0.5);
}

.site-footer__bottom-badge {
  display: inline-flex;
  align-items: center;
}

.site-footer__bottom-badge img {
  height: 24px;
  width: auto;
}

@media (max-width: 900px) {
  .site-footer__grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 560px) {
  .site-footer__grid {
    grid-template-columns: 1fr;
  }

  /* En mobile el footer queda solo con la marca (logo + texto + redes) y
     la barra de abajo (año + políticas + badge) — las 3 columnas de
     links (Institucional, Formación, Contacto) duplican navegación que
     ya está en el header/menú, y apiladas hacían un footer larguísimo. */
  .site-footer__col {
    display: none;
  }

  /* Con las columnas afuera, la marca queda sola: centrada se lee mejor
     que pegada al borde izquierdo. */
  .site-footer__brand {
    text-align: center;
  }

  .site-footer__brand img {
    margin-inline: auto;
  }

  .site-footer__brand p {
    margin-inline: auto;
  }

  .site-footer__social {
    justify-content: center;
  }

  .site-footer__bottom {
    flex-direction: column;
    gap: var(--space-2xs);
    text-align: center;
  }
}

/* ============================== Volver arriba ============================== */
.back-to-top {
  position: fixed;
  right: var(--space-md);
  bottom: var(--space-md);
  width: 46px;
  height: 46px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  background: var(--color-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--transition-base), transform var(--transition-base), visibility var(--transition-base), background var(--transition-fast);
  z-index: var(--z-header);
}

.back-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--color-accent-dark);
}

.back-to-top svg {
  width: 20px;
  height: 20px;
}

@media (max-width: 560px) {
  .back-to-top {
    right: var(--space-sm);
    bottom: var(--space-sm);
    width: 42px;
    height: 42px;
  }
}