message: perf(panel): transition opacity
diff: &::after {
  content: '';
  position: absolute;
  - top: 100%;
  + top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  rgba(225, 225, 225, 0.2) 60%,
  rgba(225, 225, 225, 0.7) 100%
  );
  + opacity: 0;
  }
  &:hover {
  outline: none;
  &::after {
  - /**
  - * use top instead of opacity to avoid GUP acceleration
  - * which might casue iframe flickering in Chrome 66
  - * @todo add back after Chrome 68
  - */
  - top: 0;
  + opacity: 1;
  }
  }
  }
  }
  .dictItem-FoldMask::after {
  - transition: top 400ms;
  + will-change: opacity;
  + transition: opacity 400ms;
  }
  .dictItem-BodyMesure {
  