Touch Margins of Kobo Touch

Hi, I have a question about margins of Kobo Touch.

I am making my epub books. It works very good but I still have a question about margins of the books. I removes all right and left margins on the book by css file shown below. When I see this book on my kobo touch I still can remove margins by the slider button (photo). Doesn't kobo Touch follow the default css margins?

------ css of the epub file

body {
font-size: 0.96em;
color: #333333;
margin-top: 0%;
margin-bottom: 0%;
margin-right: 0;
margin-left: 0;
line-height: 1.5em;
font-family: Avenir;
text-align: justify;
}

h1 {
page-break-before: always;
color: #333333;
font-size: 1.52em;
text-align: left;
font-weight: normal;
line-height: 1em;
padding-right: 0.5em;
margin-top: 1%;
margin-bottom: 1%;
}

h2 {
page-break-before: always;
color: #333333;
font-size: 1.52em;
text-align: left;
font-weight: normal;
font-style: italic;
line-height: 1em;
padding-right: 0.5em;
margin-top: 1%;
margin-bottom: 1%;
}

div.header {
width: 100%;
border-bottom-width: medium;
border-bottom-style: none;
border-bottom-color: #333333;
padding: 0em;
margin: 0em;
}

p {
line-height: 1.1em;
margin-top: 0;
margin-bottom: 0;
}

img{
width:100%;
margin-right: 0;
margin-left: 0;
border-top-style: none;
border-right-style: none;
border-bottom-style: none;
border-left-style: none;
}

div.cover {
width:100%;
text-align:center;
margin-left:auto;
margin-right:auto;
}

Attached Thumbnails