hexo-theme-reimu/source/css/_partial/top.styl

A Hakurei Reimu style Hexo theme

.sidebar-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 48px;
  height: 48px;
  background-color: var(--color-wrap);
  border-radius: 50%;
  font-family: font-icon;
  box-shadow: var(--shadow-card-hover);
  z-index: 999;
  cursor: var(--cursor-pointer) !important;

  if (hexo-config('top.position') == 'left') {
    left: 30px;
    right: auto;
  }

  .sidebar-top-taichi {
    width: 48px;
    height: 48px;
    transition: 0.3s;
    border-radius: 50%;
    opacity: 0;

    &.rotate {
      animation: rotate-all 3s linear infinite;
    }
  }

  .arrow-up {
    transition: 0.3s;
    opacity: 1;

    &:before {
      width: 48px;
      height: 48px;
      position: absolute;
      color: var(--red-1);
      font-size: 20px;
      top: 0;
      text-align: center;
      line-height: 48px;
    }
  }

  @media (hover: hover) {
    .sidebar-top-taichi {
      opacity: 1;
    }

    .arrow-up {
      opacity: 0;
    }

    &:hover {
      .sidebar-top-taichi {
        opacity: 0;
      }

      .arrow-up {
        opacity: 1;
      }
    }
  }
}

if (hexo-config('top.icon.mask')) {
  @supports (-webkit-mask: var(--top-icon) no-repeat center / 100%) {
    .sidebar-top-taichi {
      background-color: var(--red-1);
      -webkit-mask: var(--top-icon) no-repeat center / 100%;
    }
  }

  @supports (mask: var(--top-icon) no-repeat center / 100%) {
    .sidebar-top-taichi {
      background-color: var(--red-1);
      mask: var(--top-icon) no-repeat center / 100%;
    }
  }

  @supports not ( (mask: var(--top-icon) no-repeat center / 100%) and (-webkit-mask: var(--top-icon) no-repeat center / 100%) ) {
    .sidebar-top-taichi {
      background: var(--top-icon) no-repeat center / 100%;
    }
  }
} else {
  .sidebar-top-taichi {
    background: var(--top-icon) no-repeat center / 100%;
  }
}