Sub menu items dissappear when mouse moves from main menu item to sub menu item

I have main menu working fine, but when a main menu item has a sub menu, moving the mouse from the main menu to the sub menu item causes the sub menu to dissapear. Any idea why ? I have tried sub menus on all the other main items with the same result and different browsers. I am using j 3.5.1 and php 7

View at remix.victorbook.info go to book covers menu item

Hi John,
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Please check again account site. I don't login your site.
I sent you a message but did not see your reply.
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Hi John,
You custom inaccurate. You go to the menu and sub menu distance together again
Tab Dropdown Menu Style => config margin: 0px 20px 10px 0px(I edited it)
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Hi
OK. Thank you