我的代码中的这个框是否可编辑?

I have this HTML code. This code will make a box leak on my website and it's function is to validate the message sent by the user. Anw you can run the code HERE to understand what I am talking about.

My question is how to edit the box and make it appear in the middle of the screen, above the current webpage? I mean like POPUP WINDOW. It will open with PHP echo and tell the user that his message has been sent successfully. So how to make it popup in the middle of the screen when the user submits his message?

Any help will be highly appreciated. Thanks in advance.

Three things to do: 1. Your dropbox position is defined in js, modify here

var dropboxleft=screen.width/2
var dropboxtop=screen.height/2

2. Add negative margin to #dropinboxv2cover margin-left:-250px; margin-top:-150; 3. Change your current width of #dropinboxv2cover, it's too wide, change it to 500px.