Top/bottom parameter for tab close buttons

[Sasha_Chernykh]

I want slightly increase size of tab close buttons. Part of my .sublime-theme file:

   {
        "class": "tab_close_button",
        "settings": ["show_tab_close_buttons"],
        "content_margin": [15, 15]
   },

Result:

Close buttons appeared at the bottom of tab . How I can make close buttons at the center of tab?

Thanks.