index.css

body {
    font-family: 'Noto Sans','Roboto', sans-serif;
    max-width: 1000px;
    margin: auto;
}

.output-border {
    font-family: 'Source Code Pro', monospace !important;
    font-size: 0.85em;
    border: 1px dashed #999;
    border-top: none;
    padding: 4px;
    overflow-x: auto;
}

.cell-border {
    font-family: 'Source Code Pro', monospace !important;
    padding-left: 6px;
    border: 1px dashed #999;
    overflow-x: auto;
}

.chart-placeholder {
    width: 100%
}

.cell-error > .output-border {
    border-color: red;
    color: red;
    padding: 8px;
}

table {
    border: 1px solid #ddd;
    border-collapse: collapse;
}

td, th {
    white-space: nowrap;
    border: 1px solid #ddd;
    padding: 7px;
}

th {
    background-color: #eee;
}

tbody tr td:first-of-type {
    background-color: #eee;
}     

iframe {
    height: 600px;
    width: 100%;
    border: 0;
}

.center {
    text-align: center;
}

.general-output .output-border {
    background-color: #FDFDFD;
}

.json-output .output-border {
    background-color: #FDFDFD;
}

.code-cell-with-output {
    margin-bottom: 15px;
}

.flex-col {
    display: flex;
    flex-direction: column;
}

.flex-row {
    display: flex;
    flex-direction: row;
}

.flex-grow {
    flex-grow: 1;
}

.flex-center-content {
    justify-content: center;
    align-items: center;
}

.dfn-ad {
    font-family: 'Noto Sans', sans-serif;
    font-family: 'Raleway', sans-serif;
    color: white;
}