my.css

<link href='http://fonts.googleapis.com/css?family=Alegreya+Sans:100,300,400,500,700,800,900,100italic,300italic,400italic,500italic,700italic,800italic,900italic' rel='stylesheet' type='text/css'>
<link href='http://fonts.googleapis.com/css?family=Arvo:400,700,400italic' rel='stylesheet' type='text/css'>
<link href='http://fonts.googleapis.com/css?family=PT+Mono' rel='stylesheet' type='text/css'>
<link href='http://fonts.googleapis.com/css?family=Shadows+Into+Light' rel='stylesheet' type='text/css'>
<link href='http://fonts.googleapis.com/css?family=Philosopher:400,700,400italic,700italic' rel='stylesheet' type='text/css'>
<link href='http://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>

<style>

@font-face {
    font-family: "Computer Modern";
    src: url('http://mirrors.ctan.org/fonts/cm-unicode/fonts/otf/cmunss.otf');
}


#notebook_panel { /* main background */
    background: #888;
    color: #f6f6f6;
}

div.cell { /* set cell width to about 80 chars */
}

div #notebook { /* centre the content */
    background: #fff; /* white background for content */
    margin: auto;
}

#notebook li { /* More space between bullet points */
margin-top:0.8em;
}

/* draw border around running cells */
div.cell.border-box-sizing.code_cell.running {
    border: 3px solid #111;
}

/* Put a solid color box around each cell and its output, visually linking them together */
div.cell.code_cell {
    /*background-color: rgba(171,165,131,0.3); /*
    border-radius: 10px; /* rounded borders */
    padding: 1em;
    /*margin-top: 1em;*/
}

div.text_cell_render{
    font-family: 'Open Sans', Helvetica;
    line-height: 140%;
    font-size: 105%;
    /*margin-top:15px;*/
    margin-bottom:8px;
    text-align:justify;
}

/* Formatting for header cells */
.text_cell_render h1 {
    font-family: 'Open Sans',sans-serif;
    font-weight: 700;
    font-size: 30pt;
    line-height: 100%;
    display: block;
    margin-bottom: 50px;
}

.text_cell_render h2 {
    font-family: 'Open Sans', serif;
    font-weight: 100;
    font-size: 24pt;
    line-height: 100%;
    display: block;
    margin-bottom: .3em;
}    

.text_cell_render h3 {
    font-family: 'Open Sans', serif;
    font-weight: 100;
    font-size: 22pt;
    line-height: 100%;
    display: block;
    margin-bottom: 30px;
}

.text_cell_render h4 {
    font-family: 'Open Sans', serif;
}

.text_cell_render h5 {
    font-family: 'Alegreya Sans', sans-serif;
    font-weight: 300;
    font-size: 16pt;
    color: grey;
    font-style: italic;
    margin-bottom: .1em;
    margin-top: 0.1em;
    display: block;
}

.text_cell_render h6 {
    font-family: 'PT Mono', sans-serif;
    font-weight: 300;
    font-size: 10pt;
    color: grey;
    margin-bottom: 1px;
    margin-top: 1px;
}

.CodeMirror{
        font-family: "PT Mono";
        font-size: 100%;
}

.output_area {
	margin-top:20px;
}

.output_stderr {
	display:none;
	}

.output_subarea {
	display: block;
    margin: 0 auto;
}

.output_png img {
    display: block;
    margin-left: auto;
    margin-right: auto;
}

.prompt {
	visible: false;
	}

</style>