pdfmake API? Is there a list of styles, fonts, capabilities?

Here you go.. At least, uncommented below styles are supported. I tried it myself.

['font',
'fontSize',
'bold',
'italics',
'alignment',
'color',
'columnGap',
'fillColor',
'decoration',
'decorationStyle',
'decorationColor',
'background',
'lineHeight'
//'tableCellPadding'
// 'cellBorder',
// 'headerCellBorder',
// 'oddRowCellBorder',
// 'evenRowCellBorder',
// 'tableBorder'
]

You could use the above styles, as below.

var dd = {
    content: [
        { 
            text: 'This is a header, using header style', 
            style: 'header' 
        }
    ],
    styles: {
        header: {
            fontSize: 18,
            bold: true,
            background: '#ff1'
        }
    }
}