#backToTop {
      position: fixed;
      bottom: 40px;
      right: 40px;
      width: 64px;
      height: 64px;
      border-radius: 50%;
      background: rgba(255, 255, 255, 0.85);
      backdrop-filter: blur(8px);
      box-shadow: 0 12px 24px rgba(0, 0, 0, 0.2);
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      z-index: 999;
      opacity: 0;
      pointer-events: none;
      transform: scale(0.95);
      transition: opacity 0.3s ease, transform 0.3s ease;
    }

    #backToTop.show {
      opacity: 1;
      pointer-events: auto;
      transform: scale(1);
    }

    svg.progress-ring {
      position: absolute;
      top: 0;
      left: 0;
      width: 64px;
      height: 64px;
      transform: rotate(-90deg);
      shape-rendering: geometricPrecision;
    }

    circle.bg {
      stroke: #f0f0f0;
    }

    circle.progress {
      stroke: url(#gradient);
      stroke-linecap: round;
      transition: stroke-dashoffset 0.2s ease;
    }

    #backToTopIcon svg {
      width: 24px;
      height: 24px;
    }

    #backToTopIcon path {
      stroke: #333;
      stroke-width: 2.5;
      stroke-linecap: round;
      stroke-linejoin: round;
      fill: none;
    }