I just took a look at your site… It looks like the issue is with Astra not Elementor…I’d suggest contacting their development community here: https://ww.wp.xz.cn/support/theme/astra/
A crude partial fix:
.sub-menu {
top: 115px !important;
}
Added to the Additional CSS panel of the customizer.
It really needs to be in a media query so it’s not applied to mobile displays. A more proper solution would require involvement of the theme devs like Davood suggests. Or use your browser’s element inspector developer tool to help you work out a solution for yourself. You need to find the breakpoint where the theme’s mobile CSS is applied in order to compose a proper media query.