/* ============================================================
   SCROLL TO TOP — Industrial Engineering Button
   Desktop only. Fixed right. Amber on dark.
   ============================================================ */

.scroll-top {
  /* Hidden on mobile */
  display: none;
}

@media (min-width: 1024px) {

  .scroll-top {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;

    /* Position: fixed right side */
    position: fixed;
    right: 28px;
    bottom: 36px;
    z-index: 90;

    /* Size: compact industrial tile */
    width: 46px;
    padding: 12px 0 10px;

    /* Dark industrial surface */
    background: rgba(15, 23, 42, 0.88);
    border: 1px solid rgba(217, 119, 6, 0.22);
    border-radius: 4px;
    cursor: pointer;

    /* Icon + label color */
    color: rgba(217, 119, 6, 0.90);

    /* Shadow — amber glow */
    box-shadow:
      0 4px 20px rgba(15, 23, 42, 0.40),
      0 1px 4px rgba(15, 23, 42, 0.28),
      0 0 0 1px rgba(15, 23, 42, 0.60) inset;

    /* Hidden by default — appear on scroll */
    opacity: 0;
    transform: translateY(12px);
    pointer-events: none;
    transition:
      opacity 0.28s ease,
      transform 0.28s ease,
      background 0.20s ease,
      box-shadow 0.20s ease,
      border-color 0.20s ease;
  }

  /* Visible state — added by JS */
  .scroll-top.is-visible {
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
  }

  /* Hover — amber intensifies */
  .scroll-top:hover {
    background: rgba(20, 30, 52, 0.96);
    border-color: rgba(217, 119, 6, 0.55);
    color: #F59E0B;
    box-shadow:
      0 6px 28px rgba(15, 23, 42, 0.48),
      0 2px 8px rgba(15, 23, 42, 0.30),
      0 0 16px rgba(217, 119, 6, 0.12),
      0 0 0 1px rgba(15, 23, 42, 0.70) inset;
    transform: translateY(-2px);
  }

  /* Active — pressed down */
  .scroll-top:active {
    transform: translateY(1px) scale(0.97);
    background: rgba(10, 16, 32, 0.96);
  }

  /* Vertical progress track — thin amber line on left edge */
  .scroll-top__track {
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(
      to bottom,
      rgba(217, 119, 6, 0.80) 0%,
      rgba(217, 119, 6, 0.20) 100%
    );
    border-radius: 0 0 0 4px;
  }

  /* Icon */
  .scroll-top__icon {
    width: 26px;
    height: 26px;
    display: block;
    flex-shrink: 0;
  }

}