Capture one element

capture.js

var async = require('async'),
    sizes = [
        [1280, 720],
    ];

function capture(sizes, callback) {
    var page = require('webpage').create();
    page.viewportSize = {
        width: sizes[0],
        height: sizes[1]
    };
    page.zoomFactor = 1;
    page.open('http://localhost:8000/dist', function (status) {
        var filename = sizes[0] + 'x' + sizes[1] + '.png';

        var data = page.evaluate(function() {
          return document.querySelector('section.pricing-4.inverse').getBoundingClientRect();
        });

        console.log(data.top);
        page.clipRect = data;
        page.render('./screenshots/' + filename);
        page.close();
        callback.apply();
    });
}

async.eachSeries(sizes, capture, function (e) {
    if (e) console.log(e);
    console.log('done!');
    phantom.exit();
});