Hi there!
Thanks for reaching out.
Would you please share your site url here to check the issue for you? However, the following code in your custom CSS should work:
.sp-megamenu-parent>li>a, .sp-megamenu-parent>li>span {
padding: 0 10px;
font-size: 14px;
}
You can reduce the value of the menu item font size and padding among the items both in the following code.
Please check the below link for references:
https://www.joomshaper.com/documentation/helix-framework/customization-tips#how-to-reduce-space-between-menu-items
Best regards,