move 50px layout

Hello everybody,
I change my blog theme and i disable the mobile responsive so now i have a desktop view from mobile andd tablets device.GOOD!
But when i disable that,the desktop layout broken with some cm, i think 50px.
What code and where must be paste to fit the theme on desktop?

Please help me

If you have a html file you can add this code with in html body tag or if you have a css file you can add it there also.

html,body
{
height:100%;
}
body
{
padding:0;
}


/** if you are creating a page just declare size in % because the screen resolution will change for every PC , so if you declare 100% it will allocate the size with respect to the screen size.***/