button not centered

Hi there,

I installed the topofthepage plugin and I must say I love it!

Only one litte problem:
the button is not really centered. On the PC browser page this is not a bit ptoblem, but on the smartphone it looks odd:
www.stefan-schoch.de

What can I do to fix this?

Thx,
Stefan

Thx!

That's weird. On the PC the button seems to be centered now, on the smartphone it a bit too far left. And the bottom margin seems to be bigger now (shall be 15px).
And the button is to narrow, so the text is broken into two lines (shall be one line).

This is how my CSS looks like:

#plg_system_topofthepage{
border:1px solid #000;border-radius:4px;margin:15px;padding-left:20px;padding-right:20px; padding-top:4px; padding-bottom:4px;background-color:#D2D2D2;color:#000;left: 50%;margin-right: 50%;transform: translate(-50%,-50%);}

#plg_system_topofthepage:hover{background-color:#008BA3;color:#ffff;}

Any idea?