phantomjs

c.js

// Usage: phantomjs c.js

var page = require('webpage').create();

var url = 'c.html';

page.open(url, function(status){
    window.setTimeout(function () {
        var height = page.evaluate(function(){
            return document.body.scrollHeight;
        });
        page.clipRect = {top: 0, left: 0, width: 406, height: height};
        page.render('c.png', {quality: 90});
        phantom.exit();
    }, 200);
});