我在尝试解决一个简单的动画问题，即在悬停时背景图像淡入淡出。尽管我已经定义了关键帧，但网页浏览器显示未定义：

.elementor-section.elementor-element.core-range
     > .elementor-container:hover
     .product-image::before {
     animation: coreRangeBackground 0.3s ease-in-out 0.3s;
     animation-fill-mode: forwards;
  }

  @keyframes coreRangeBackground {
     100% { background-image: url("./images/core-range-bg.svg"); }
  }

  .elementor-section.elementor-element.phases-of-the-moon
     > .elementor-container:hover
     .product-image::before {
     animation-name: phasesMoonBackground;
     animation-duration: 0.3s;
     animation-timing-function: ease-in-out;
     animation-delay: 0.3s;
     animation-fill-mode: forwards;
  }

  @keyframes phasesMoonBackground {
     100% { background-image: url("./images/phases-of-the-moon-bg.svg"); }
  }

编辑：无法对背景图像进行动画处理，改为使用不透明度

图像以渐变的方式淡入，但在取消悬停后，它立即切换到没有图像，而不是渐出。

.elementor-section.elementor-element.product-card
     > .elementor-container
     .product-image::before {
     transition: all 0.3s ease-in-out;
     position: absolute;
     width: 100%;
     height: 100%;
     background-repeat: no-repeat;
     background-size: cover;
     top: 0;
     left: 0;
     display: block;
     content: "";
  }

  .elementor-section.elementor-element.core-range
     > .elementor-container:hover
     .product-image::before {
     animation: productCardBackgroundHover 0.3s ease-in-out;
     animation-fill-mode: forwards;
     background-image: url("./images/core-range-bg.svg");
  }

  .elementor-section.elementor-element.phases-of-the-moon
     > .elementor-container:hover
     .product-image::before {
     animation: productCardBackgroundHover 0.3s ease-in-out;
     animation-fill-mode: forwards;
     background-image: url("./images/phases-of-the-moon-bg.svg");
  }

  @keyframes productCardBackgroundHover {
     0% { opacity: 0; }
     100% { opacity: 1; }
  }