/* Shell styles — back-to-top (rotating border glow, ELMS cyan) */

@property --cta-border-angle {
  syntax: "<number>";
  inherits: true;
  initial-value: 0;
}

@keyframes footer-cta-border-spin {
  to { --cta-border-angle: 360; }
}

.back-to-top--glow {
  --btt-speed: 14s;
  --btt-border-w: 1.5px;

  position: fixed;
  right: clamp(0.85rem, 0.45rem + 1.5vw, 1.75rem);
  bottom: clamp(0.85rem, 0.45rem + 1.5vw, 1.75rem);
  z-index: 90;
  width: 3.5rem;
  height: 3.5rem;
  margin: 0;
  box-sizing: border-box;
  border-radius: 50%;
  padding: var(--btt-border-w);
  display: grid;
  place-items: stretch;
  cursor: pointer;
  text-decoration: none;
  color: #fff;
  background: conic-gradient(
    from calc(var(--cta-border-angle, 0) * 1deg),
    rgba(0, 80, 120, 0.35)   0%,
    rgba(0, 120, 170, 0.55) 28%,
    rgba(0, 180, 216, 0.82) 42%,
    rgba(160, 235, 255, 1)  50%,
    rgba(0, 180, 216, 0.82) 58%,
    rgba(0, 120, 170, 0.55) 72%,
    rgba(0, 80, 120, 0.35) 100%
  );
  animation: footer-cta-border-spin var(--btt-speed) linear infinite;
  box-shadow:
    0 0 16px rgba(0, 180, 216, 0.16),
    0 0 36px rgba(0, 180, 216, 0.07);
  transform: none;
  transition:
    transform 280ms cubic-bezier(0.22, 1, 0.36, 1),
    box-shadow 0.5s ease;
}

.back-to-top--glow::before {
  content: "";
  position: absolute;
  inset: -8px;
  z-index: -1;
  border-radius: 50%;
  pointer-events: none;
  background: conic-gradient(
    from calc(var(--cta-border-angle, 0) * 1deg),
    transparent 0%,
    transparent 32%,
    rgba(0, 180, 216, 0.22) 42%,
    rgba(120, 220, 255, 0.35) 50%,
    rgba(0, 180, 216, 0.22) 58%,
    transparent 68%,
    transparent 100%
  );
  filter: blur(14px);
}

.back-to-top--glow[hidden] {
  display: none !important;
}

.back-to-top__inner {
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
  border-radius: 50%;
  background: rgb(5, 12, 24);
}

.back-to-top--glow.is-visible:hover,
.back-to-top--glow.is-visible:focus-visible {
  transform: translateY(-4px);
  box-shadow:
    0 0 24px rgba(0, 180, 216, 0.34),
    0 0 56px rgba(0, 180, 216, 0.14),
    0 0 96px rgba(0, 180, 216, 0.06);
}

.back-to-top--glow.is-visible:hover::before,
.back-to-top--glow.is-visible:focus-visible::before {
  filter: blur(20px);
}

.back-to-top__icon {
  position: relative;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 1.5rem;
  height: 1.5rem;
  font-size: 1.375rem;
  line-height: 1;
  color: #00b4d8;
  transform: translateY(-1px);
  font-variation-settings: "FILL" 1, "wght" 500, "GRAD" 0, "opsz" 24;
  transition: transform 260ms ease, color 260ms ease;
}

.back-to-top--glow.is-visible:hover .back-to-top__icon,
.back-to-top--glow.is-visible:focus-visible .back-to-top__icon {
  transform: translateY(-3px);
  color: rgba(160, 235, 255, 1);
}

@media (prefers-reduced-motion: reduce) {
  .back-to-top--glow {
    animation: none !important;
    background: rgba(0, 100, 150, 0.45);
  }
}