Padding after stretch the Browse and less file

Something new … When I stretch the Browse he receives income from the left, and I see the codes .less
I can not find them in folders, can someone please help me with this?

the code that i have

html, body
height: 100%;
width: 100%;
margin: 0;
padding: 0;
background-color: #555; }

  • { margin:0; padding:0; box-sizing:border-box; }