semi-design/packages/semi-ui/dropdown/_story/InHoverElements/index.scss

.demo-in-hover-elements {
    width: 200px;
    height: 100px;
    background-color: var(--semi-color-primary-light-default);
    padding: 20px;

    .action {
        display: none;
    }

    &:hover {
        .action {
            display: block;
        }
    }
}